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OceanaGold Drills Multiple Ore-Grade Intercepts at Horseshoe Extension at Haile and Extends Mineralization at Depth at Didipio

Drill Results

April 3, 2024

News Release

OceanaGold Drills Multiple Ore-Grade Intercepts at Horseshoe

Extension at Haile and Extends Mineralization at Depth at Didipio

(VANCOUVER) OceanaGold Corporation (TSX: OGC; OTCQX:OCANF) (“OceanaGold” or the “Company”)

is pleased to provide results from exploration and resource conversion drilling for Haile and Didipio.

Gerard Bond, President & CEO of OceanaGold, said “We are off to an excellent start to the year with our

exploration and resource conversion programs with results continuing to reinforce the growth potential we

see within our existing mine footprints. Results from the Horseshoe Extension target at Haile, outside of

existing resources, reflect the first drilling we have completed into this target from underground. We have

encountered similar grades and widths to the Horseshoe orebody, and the Horseshoe Extension target is

close to planned future underground development.”

“Results at Didipio continue to extend mineralization at depth and we have now drilled a second hole below

the existing resource as a follow-up to last year’s drilling. This result extends known mineralization a further

~150 metres at depth into Panel 4, and a total of ~200 metres below the current inferred resource. Lastly,

I am delighted we are now drilling at the Napartan regional target, located 9 kilometres northwest of Didipio,

with two holes of a 2,500 metre program now completed, awaiting assay results.”

• Haile drill highlights include (core length):

• 34.9 m @ 7.6 g/t Au, Horseshoe (UGD0026 - conversion)

• 39.3 m @ 5.8 g/t Au, Horseshoe Extension (UGD0044 - extensional)

• 34.4 m @ 4.6 g/t Au, Horseshoe Extension (UGD0026 - extensional)

• 34.3 m @ 4.3 g/t Au, Horseshoe Extension (UGD0035 - extensional)

• Didipio drill highlights include (core length):

• 103 m @ 2.02 g/t AuEq, Eastern Monzonite (RDUG515 - conversion)

• 91 m @ 2.24 g/t AuEq, Eastern Monzonite (RDUG517 – conversion)

• 72 m @ 2.28 g/t AuEq, Eastern Monzonite (RDUG518 – conversion)

• 87m @ 1.43 g/t AuEq, Eastern Monzonite (RDUG522 – extensional)

• 66 m @ 1.76 g/t AuEq, Feldspar Porphyry (RDUG625A – extensional)

• 35 m @ 1.06 g/t AuEq, Northern Balut (RDUG523 – extensional)

Haile Exploration Update

Resource conversion and ex tensional drilling from Horseshoe Underground continues with 2,142 metres

completed of a planned 10,605 metres this year. The results from 8 holes drilled at Horseshoe Extension

target and lower Horseshoe at the end of 2023 and the beginning of 2024 have been received. Highlights

from this drilling include 34.9 m @ 7.60 g/t Au from hole UGD0026 targeting conversion of the lower

Horseshoe Inferred resource (result received after data cut-off for 2023 end of year Reserve and Resource

model update) and 39.3 m @ 5.8 g/t Au from hole UG D0044, among others, targeting resource growth at

Horseshoe Extension.

Horseshoe Extension is a zone of mineraliz ation located approximately 200 metres southwest of the

Horseshoe orebody with similar plunge on the southern limb of the northeastern striking antiform (Figure

1). M ineralization is of the same character as Horseshoe, occurring along a mineralized

metasediment/metavolcanic contact. Continuity of the lower Horseshoe Extension mineralization is

confirmed (Figure 1, UGD0040, 41, 44, 45).

Drilling in 2024 will continue to target the Horses hoe Extension as more optimal drill locations become

available with more underground development and will also target infill drilling of inferred mineralization at

lower Horseshoe.

Figure 1: Schematic long section (looking north-west) showing Horseshoe and Horseshoe

Extension mineralisation at Haile and recent drillholes annotated.

1. Inclusive of Reserves

2. Based on reported Reserves and Resources for the year ended 2023

Didipio Exploration Update

Since the February 2, 2024 news release 6,763 metres of extensional and resource conversion drilling in

twenty-three holes has been completed from Didipio underground (Figure 2).

Figure 2: Simplified geologic plan showing Didipio drilling since February 2024 press release with

significant intercepts and approximate mineralized envelope at the 2,190mRL. Sections A-A’

through F-F’ also shown.

Extensional Drilling

Extensional drilling has been achieved by extending resource conversion drill holes beyond the resource

shell to the north, northeast, and at depth t o approximately 1,700 mRL; extending mineralisation

approximately 750 metres below the bottom of the open pit . Extensional drilling has focused on (a) depth

extension of Balut Dyke mineralization on the northern side of the Syenite Porphyry (Figure 3, section A –

A’), and (b) depth extension of mineralization within the Monzonite in Panel 4 (Figure 3, section B – B’).

Extensional hole RDUG522 was completed to follow up on the previous success of hole RDUG611 (72 m

@ 3.40 g/t AuEq) reported in August 2023 (Figure 3, B -B’) which has opened up a lower zone of

mineralization to the north and at a depth of ~1,900 mRL and below. An intercept returning 87 m @ 1.43

g/t AuEq (RDUG522) has confirmed mineralization extends for over 150 metres further below RDUG611

down to 1,710mRL (Figure 3), opening up a zone of 200 metres vertical extent below the reported Inferred

resource. Further drilling will be undertaken in 2024 to define the extent of this new mineralization zone.

Hole RDUG523 returned a result of 35 m @ 1.06 g/t AuEq and confirmed a 70 m vertical continuation of

the recently identified Balut Dyke on the northern side of the Syenite with similar thickness below previously

reported RDUG500 with 45.4 m @ 2.51 g/t AuEq (Figure 3). Mineralization of the Balut on the north remains

open along strike and at depth while its analogue defined at a higher elevation on the south also remains

open at depth and to be tested to a similar elevation (i.e. 1,900mRL).

In addition, hole RDUG627 has identified an additional zone of minerali zation further east (Figure 4 , F-F’)

intersecting 15 m @ 3.32 g/t AuEq associated with a nother Feldspar Porphyry. The recent discovery of

three new mineralized intrusives in the east highlights the prospectivity that remains for further mineralized

areas.

Figure 3: Long sections (A-A’ and B-B’) of geological model with new intercepts annotated.

Resource Conversion Drilling

Resource Conversion drilling has focused on (i) conversion of the inferred resource within the Monzonite

Porphyry directly east of the Syenite Porphyry within Panel 3 (< 2,100 mRL, Figure 4, C-C’, D-D’), and (ii)

infill drilling of the minerali zed Eastern Breccia and Feldspar Porphyry in the east (Figure 4, section E-E’

and F-F’). These drill programs broadly confirm and provide improved confidence in the inferred grade

estimates as calculated in the end of year 2023 annual resource and reserve model.

Follow-up drilling on two mineralized intrusives discovered in 2022 (Eastern Breccia and Feldspar Porphyry)

demonstrates continuity of mineralization with both zones remaining open at depth and potentially

expanding the mineralized Feldspar Porphyry (Figures 4, E-E’, F-F’). Hole RDUG625A has confirmed the

continuity of mineralization within the Feldspar Porphyry while holes RDUG626 and RDUG623 appear to

have closed off this mineralization to the east.

Figure 4: Geological sections C-C’, D-D’, E-E’ and F-F’ showing conversion drilling.

Napartan Exploration Update

Regional exploration in 2024 includes advancing the Napartan initial drill target, 9 km north-west of the

Didipio mine. Surface mapping and sampling has identified a Cu-Au mineralised pegmatite similar in nature

to the Balut Dyke and an important ores sourc e at Didipio. Drilling at Napartan began on March 15, 2024,

with one drill rig mobilized. Two holes have now been completed of a 2,500 m program budgeted for 2024,

with assay results pending.

Table 1: Haile drill intersections. Intervals are core length, not true width. “Conversion” intercept is within the current

resource model shell, while “Extensio nal” are intercepts outside the current resource model shell. NSR = No Significant

Result.

Hole ID From To Interval Au Target Category

(m) (m) (m) (g/t)

UGD0026 312.6 347.5 34.9 7.60 Horseshoe Conversion

UGD0032 200.9 211.9 11.1 2.15 Horseshoe Extension Extension

And 229.5 238.5 9.1 3.15 Horseshoe Extension Extension

UGD0035 225.4 229.8 4.4 2.54 Horseshoe Extension Extension

And 241.4 248.1 6.7 11.70 Horseshoe Extension Extension

And 262.4 296.7 34.3 4.32 Horseshoe Extension Extension

Including 285.9 293.9 8.0 10.47 Horseshoe Extension Extension

UGD0036 NSR Horseshoe Extension Extension

UGD0040 318.2 333.5 15.2 8.24 Horseshoe Extension Extension

Including 322.8 332.0 9.2 12.15 Horseshoe Extension Extension

And 341.1 360.1 19.0 3.12 Horseshoe Extension Extension

UGD0041 315.2 356.3 41.2 3.58 Horseshoe Extension Extension

Including 338.8 343.6 4.8 11.89 Horseshoe Extension Extension

UGD0044 312.5 351.7 39.3 5.83 Horseshoe Extension Extension

Including 319.6 336.7 17.2 10.34 Horseshoe Extension Extension

UGD0045 320.4 354.8 34.4 4.60 Horseshoe Extension Extension

including 337.2 341.1 3.9 32.09 Horseshoe Extension Extension

Table 2: Didipio drill intersections. Intervals are core length, not true width. “Conversion” are intercepts within the current

resource model shell, while “Extensional” are intercepts outside the current resource model shell.

Hole ID From To Interval Au Cu AuEq Target Category (m) (m) (m) (g/t) (%) (g/t)

RDUG509 117 185 68 0.60 0.35 1.08 Monzonite Conversion

RDUG510 78 136 58 0.64 0.28 1.02 Monzonite Conversion

And 143 199 56 0.39 0.25 0.74 Monzonite Conversion

RDUG511 81 181 100 0.79 0.36 1.29 Monzonite Conversion

And 191 237 46 0.67 0.34 1.14 Monzonite Conversion

RDUG512 45 59 14 2.26 4.32 8.27 Monzonite Conversion

And 66 120 54 0.58 0.33 1.04 Monzonite Conversion

And 140 192 52 0.51 0.32 0.95 Monzonite Conversion

RDUG513 91 148 57 0.93 0.36 1.42 Monzonite Conversion

Including 128 136 8 2.35 0.64 3.25 Monzonite Conversion

RDUG514 43 52 9 1.97 1.00 3.35 Monzonite Conversion

and 156 210 54 1.34 0.54 2.08 Monzonite Conversion

Including 169 178 9 3.31 1.27 5.07 Monzonite Conversion

RDUG515 64 167 103 1.32 0.50 2.02 Monzonite Conversion

RDUG516 120 139 19 1.31 0.58 2.11 Monzonite Conversion

And 169 219 50 0.65 0.31 1.08 Monzonite Conversion

Hole ID From To Interval Au Cu AuEq Target Category

(m) (m) (m) (g/t) (%) (g/t)

RDUG517 72 163 91 1.61 0.46 2.24 Monzonite Conversion

RDUG518 62 134 72 1.40 0.63 2.28 Monzonite Conversion

And 156 178 22 4.21 0.61 5.07 Monzonite Conversion

Including 159 165 6 13.04 1.10 14.57 Monzonite Conversion

And 184 251 67 1.20 0.28 1.60 Monzonite Conversion

RDUG519 128 151 23 1.03 0.38 1.56 Monzonite Conversion

And 175 240 65 1.04 0.37 1.56 Monzonite Conversion

RDUG520 83 131 48 2.00 0.47 2.65 Monzonite, Sth Balut

Extension Conversion

Including 105 116 11 5.01 0.84 6.17 Monzonite, Sth Balut

Extension Conversion

RDUG521 123 158 35 1.80 0.55 2.57 Monzonite, Sth Balut

Extension Conversion

RDUG522 376 463 87 1.01 0.30 1.43 Monzonite Extensional

And 469 503 34 0.52 0.24 0.85 Monzonite Extensional

RDUG523 315 350 35 0.83 0.17 1.06 Northern Balut Extensional

And 366 384 18 1.26 0.28 1.65 Northern Balut Extensional

RDUG623 23 75 52 0.77 0.45 1.40 Eastern Breccia Conversion

RDUG624 14 58 44 0.54 0.49 1.22 Eastern Breccia Conversion

And 150 190 40 0.45 0.35 0.93 Monzonite Conversion

RDUG625A 20 87 67 0.50 0.33 0.96 Eastern Breccia Conversion

And 196 262 66 1.02 0.54 1.76 Monzonite, Feldspar

Porphyry Extensional

RDUG626 24 64 40 0.65 0.45 1.27 Eastern Breccia Conversion

RDUG627 11 68 57 0.93 0.50 1.62 Eastern Breccia Conversion

And 197 212 15 2.35 0.70 3.32 Monzonite, Feldspar

Porphyry Extensional

Including 206 212 6 4.57 1.13 6.14 Monzonite, Feldspar

Porphyry Extensional

RDUG628 37 78 41 0.71 0.43 1.32 Eastern Breccia Conversion

RDUG629 60 132 73 0.79 0.44 1.40 Eastern Breccia Conversion

RDUG630 40 62 22 0.56 0.59 1.38 Eastern Breccia Conversion

For further information relating to drill hole data please refer to the Company's webs ite

at https://investors.oceanagold.com/additional-drillhole-data.

For further information please contact:

Investor Relations:

Rebecca Harris, Director, Investor Relations

Tel: +1 604 678 4095

[email protected]

Media Relations:

Louise Burgess, Director, Communications

Tel: 1 (604) 403-2019

[email protected]