OceanaGold Confirms Continuity and Extension of Newly Defined Southern High-Grade Zone at Wharekirauponga

VANCOUVER, BC, April 1, 2026 /PRNewswire/ – OceanaGold Corporation (TSX: OGC) (OTCQX: OCANF) (“OceanaGold” or the “Company”) announces results from 6 drill holes from the ongoing exploration and resource conversion program at Wharekirauponga, located approximately 10 kilometres (“km”) to the north of the Company’s Waihi operation in New Zealand.

Wharekirauponga Drilling Highlights (estimated true width):

• 14.9 m @ 16.3 g/t Au from 466.5 m, EG Vein (WKP144B)
• 5.4 m @ 25.8 g/t Au from 483.4 m, EG Vein (WKP144A)
• 5.5 m @ 24.1 g/t Au from 623.6 m, EG Vein (WKP124N)
• 6.4 m @ 19.1 g/t Au from 470.7 m, EG Vein (WKP144C)
• 5.4 m @ 6.6 g/t Au from 443.5 m, EG HW Veins (WKP144B)
• 2.5 m @ 10.3 g/t Au from 436.9 m, EG HW Veins (WKP144B)

Gerard Bond, President and CEO of OceanaGold, said “Today’s drill results from Wharekirauponga continue to demonstrate the upside of this exceptional orebody. Drilling indicates a newly emerging high-grade zone that sits outside of reserves, at the southern extent of the known deposit. Importantly, the newly defined high-grade zone is located closer to the planned underground access. With Wharekirauponga remaining open in multiple directions, we remain well positioned to drive shareholder value through continued resource growth and conversion as we increase the amount of drilling this year.”

Drill results can be viewed in 3D using VRIFY at the following link:
https://vrify.com/meetings/recordings/852c6a5b-6fe4-488f-b10f-0ca92c8aae87

Wharekirauponga Drill Results Overview

Since the Company’s November 25, 2025 news release, a total of 6 drill holes have been completed and results returned from the EG, hanging wall (“HW”) and footwall (“FW”) Veins, collectively referred to as the “EG Vein zone” (Figure 1). Notably, drill results in the southern portion of the EG Vein continue to define the emergence of a new high-grade zone that is on the periphery of the Inferred Mineral Resource but sits outside the Mineral Reserves.

East Graben (“EG”) Vein

Drilling from site 9 returned multiple wide, high-grade intercepts demonstrating the continuity of the system in the southern area. Results included 14.9 m @ 16.3 g/t Au (WKP144B) and 5.4 m @ 25.8 g/t Au (WKP144A) (Figure 2). These results support increased confidence in the resource model and extend high-grade mineralization up-dip on the southern portion of the resource. The newly defined southern high-grade zone, encompassing seven drill holes (including previously reported holes) averaging above 160 gram metres, currently spans 150 metres in strike. This area remains open in multiple directions and is a target for follow-up drilling later this year.

At drill site 8, conversion drilling results were above expectations, including 5.5 m @ 24.1 g/t Au (WKP124N). While previous interpretations suggested that the upper extent of the EG Vein was geometrically constrained, new results suggest that the mineralization is dipping more shallowly than previously interpreted and there remains the potential for further up-dip extensions of the EG Vein (Figure 3). Follow-up drilling is also planned for this area.

Hanging Wall and Footwall Veins

The HW and FW Veins and associated extensional sub-parallel structures that lie immediately to the east and west, respectively, of the EG Vein also yielded strong results. WKP144-series (A,B,C) holes returned high-grade mineralization including 5.4 m @ 6.6 g/t Au (WKP144B) and 2.5 m @ 10.3 g/t Au (WKP144B) (Figure 4). These results highlight a zone of high‑grade mineralization outside of the current resource model that are largely unconstrained due to limited drilling, yet lies in immediate proximity to the EG Vein and represents a target for future drilling.

Wharekirauponga 2026 Exploration Program

Three drill rigs are operating at drill sites 1, 8, and 9 at Wharekirauponga (Figure 1). We expect to add an additional two drill rigs during the second quarter of 2026 on new drill platforms in accordance with the permit approval in December 2025. Drilling for 2026 will continue to focus on improving resource confidence and further resource growth.

Table 1: Wharekirauponga drill intersections subsequent to the press release dated November 25, 2025, results update

For further information relating to drill hole data please refer to the Company’s website at https://oceanagold.com/operations/additional-drillhole-data.

About OceanaGold

OceanaGold is a global intermediate gold and copper producer committed to safely and responsibly maximizing the generation of Free Cash Flow from our operations and delivering strong returns for our shareholders. We have a portfolio of four operating mines: the wholly-owned Haile Gold Mine in the United States of America; the wholly-owned Macraes and Waihi operations in New Zealand; and the 80%-owned Didipio Mine in the Philippines.

Qualified Person Statement

The scientific and technical information in this press release has been reviewed and approved by Mr. Leroy Crawford-Flett, a Chartered Professional Member of the Australasian Institute of Mining and Metallurgy and a qualified person under National Instrument 43-101 – Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators (“NI 43-101”). Mr. Crawford-Flett is the Exploration & Geology Manager of the Waihi Operation.

Quality Assurance and Quality Control (“QA/QC”)

All exploration samples are assayed for gold by 30g fire assay with AAS finish. Since mid-2022, drill core sample intervals where visible electrum is logged are followed up by a subsequent screen fire assay after the routine 30g fire assay. Core samples were prepared and analyzed at the independent SGS Waihi NZ Ltd laboratory (Au by 30g fire assay and Ag by aqua regia digest and 0.3gm AAS finish. Samples post April 2024 with Ag, As, Sb. Hg and S by ICP-MS after DIG12R Digest). Selected pulps are periodically sent to the independent ALS laboratory in Brisbane for a 4-acid digestion and 42 or 48 element ICP geochemical analysis. 

Quality of exploration assay results has been monitored in the following areas: 

• Sample preparation at the independent SGS Waihi and Westport labs through sieving of jaw crush and pulp products; 
• Monitoring of assay precision through routine generation of duplicate samples from a second split of the jaw crush and calculation of the fundamental error; and
• Monitoring of accuracy of the primary SGS assay and ALS results through insertion Certified Reference Materials (“CRMs”) and blanks into sample batches. 

Blank, duplicate and CRM results are reviewed prior to uploading results in the acQuire database and again on a weekly basis. The QA/QC protocol at Waihi requires CRMs to be reported to within 2 standard deviations of the certified value, for preparation duplicates to have a relative difference (R-R1/mean RR1) of no greater than 10%, and for blanks to not exceed more than 5 times the lower detection value of the assay method. Failure in any of these thresholds triggers an investigation and, if appropriate, re-assay. Drill core is stored within secure facilities on site to which access is controlled. Site employees transport samples to the analytical laboratory which is also a secured facility. The SGS Waihi NZ Ltd laboratory is an independent commercial geochemistry and energy assay laboratory with ISO 17025: 2017 accreditation, audited by an external consultant in 2020, and is inspected on a monthly basis by OceanaGold geologists. No sampling risks have been recorded during these visits.

Technical Report

For further information, please refer to the following NI 43-101 technical report available on the SEDAR+ website at www.sedarplus.ca under the Company’s profile or on the Company’s website at www.oceanagold.com: “NI 43-101 Technical Report – Waihi District Study Pre-feasibility Study, New Zealand” dated December 11, 2024, with an effective date of June 30, 2024, prepared by D. Townsend, L Crawford-Flett, K. Hollis, E Leslie, and T. Maton (OceanaGold).

Cautionary Statement for Public Release

This press release contains certain “forward-looking statements” and “forward-looking information” (collectively, “forward-looking statements”) within the meaning of applicable Canadian and United States securities laws which may include, but is not limited to, statements with respect to: the estimation, realization and classification of Mineral Reserves and Mineral Resources; costs and timing of future exploration and drilling programs for 2026; exploration expenditures; the anticipated doubling of drill sites and timing for the additional two drill platforms in accordance with the recently approved Fast Track permit application; anticipated deliverance of shareholder value through continued Mineral Resources growth and conversion; the timing and receipt of required permits, certifications, approvals, consents and renewals under applicable legislation; social licence to operate and stakeholder relationships; foreign operations and political, economic and regulatory conditions in the jurisdictions in which we operate; and governmental regulation of exploration operations. Forward-looking statements and information relate to future performance and reflect the Company’s expectations regarding the generation of Free Cash Flow, execution of business strategy, future growth, future production, estimated costs, results of operations, business prospects and opportunities of OceanaGold and its related subsidiaries. All statements in this press release that address events or developments that the Company expects to occur in the future are forward-looking statements. Forward-looking statements are statements that are not historical facts and are generally, although not always, identified by words such as “may”, “plans”, “expects”, “projects”, “is expected”, “scheduled”, “potential”, “estimates”, “forecasts”, “intends”, “targets”, “aims”, “anticipates” or “believes” or variations (including negative variations) of such words and phrases, or may be identified by statements to the effect that certain actions, events or results “may”, “could”, “would”, “should”, “might” or “will” be taken, occur or be achieved.

Forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the Company’s actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. Such risks include, among others: the risk of not achieving production estimates, forecasts or Guidance; inaccuracy of Mineral Reserves, Mineral Resources and operating and capital cost estimates; the actual results of current and future production, development and/or exploration activities; possible variations of ore grade, metallurgy or recovery rates; changes in mine plans, project parameters or assumptions as plans continue to be refined; delays in, or inability to complete, development or construction or expansion activities or to re-commence or sustain operations as planned; failures or underperformance of plant, equipment, infrastructure or processes; geotechnical risks or events, including open pit wall stability, crown pillar failure, land subsidence and tailings dam failures; challenges associated with effective water management; environmental, health and safety and climate-related risks; risks related to community acceptance, stakeholder engagement and social licence to operate; competition for mineral properties and other growth opportunities; legal and regulatory challenges to current and future permits, certifications, approvals or licences; adverse judicial, regulatory or governmental decisions; delays in, or inability to obtain, financing or governmental approvals on acceptable terms; changes in laws, regulations, taxation regimes, regulated accounting standards or their interpretation or application; the risks associated with operating in foreign jurisdictions, including political instability, changes in policy or law, civil unrest or conflict; fluctuations in the prices of gold, copper and silver; general business, economic and market conditions (including changes in global, national or regional financial, credit, currency or securities markets); changes or developments in global, national or regional political and social conditions; fluctuations in foreign exchange rates, including the value of the U.S. dollar relative to the Canadian dollar or the New Zealand dollar; inflationary pressure; labour availability, retention and turnover; accidents, labour disputes and other operational risks of the mining industry; limitations of insurance coverage or uninsured risks; the conclusions of economic evaluations, studies and models; and those other factors identified and described in more detail in the section entitled “Risk Factors” in the Company’s most recent Annual Information Form prepared and filed with securities regulators which is available on SEDAR+ at www.sedarplus.ca under the Company’s name and on the Company’s website. The list is not exhaustive of the factors that may affect the Company’s forward-looking statements.

There are no assurances the Company can fulfil forward-looking statements. Such forward-looking statements are only predictions based on current information available to Management as of the date that such predictions are made; actual events or results may differ materially as a result of risks facing the Company, some of which are beyond the Company’s control. Although the Company believes that any forward-looking statements contained in this press release are based on reasonable assumptions, readers cannot be assured that actual outcomes or results will be consistent with such statements. Accordingly, readers should not place undue reliance on forward-looking statements. The Company expressly disclaims any intention or obligation to update or revise any forward-looking statements and information, whether as a result of new information, events or otherwise, except as required by applicable securities laws.

Cautionary Statements for United States Readers

The scientific and technical disclosure in this press release was prepared in accordance with NI 43-101, which differs from the scientific and technical disclosure requirements of the U.S. Securities and Exchange Commission (the “SEC”) that are applicable to domestic United States reporting companies. Any Mineral Reserves and Mineral Resources reported by the Company in accordance with NI 43-101 may not qualify as such under SEC standards, including Subpart 1300 of Regulation S-K under the United States Exchange Act of 1934, as amended. Accordingly, Mineral Resources and Mineral Reserves information and other scientific and technical information contained or referenced in this press release may not be comparable to similar scientific and technical information disclosed by United States public companies subject to the reporting and technical disclosure requirements of the SEC. Historical results or feasibility models presented herein are not guarantees or expectations of future performance.

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SOURCE OceanaGold Corporation