Sea Lion Operator’s Update

24 March 2025

Rockhopper Exploration plc("Rockhopper" or the "Company")

Sea Lion Operator's Update

Rockhopper Exploration plc (AIM: RKH), the oil and gas company with key interests in the North Falkland Basin ("NFB"), notes the recent publication by Navitas Petroleum LP ("Navitas" or the "Operator") of and an updated NFB independent resource report conducted by Netherland Sewell & Associates ("NSAI") (the "March 2025 NSAI Independent Report") on behalf of Navitas. The report reflects work carried out to mature the resource base and accelerates later phases of the development programme in the build up to FID. Overall resources at Sea Lion remain unchanged. As a result of the work carried out, a significant number of barrels have been moved from 'Development On Hold' to 'Development Pending' classification.

March 2025 NSAI Independent Report

The new March 2025 NSAI report, which Rockhopper has not reviewed, categorises the Sea Lion resources into the following developments:

· Northern area, 3 phases

· Central area, 2 phases

· Northern Area Phases 1 and 2 will be developed using a redeployed and upgraded FPSO that is expected to be secured upon FID.

· Northern Area phase 3 and the Central Area Phases 1 and 2 will require a substantially larger replacement FPSO to be identified and secured.

The Development on Hold category of 178 MMbbls 2C includes gross resources within Sea Lion and Isobel/Elaine, that could be developed under future phases but for which there is currently no published development plan.

Key Information

2C Contingent Resources (Development Pending) phased development concept for the Sea Lion field:

· 64 wells

· Phased Development

Northern Area

Phase 1 11 wells, 6 pre drilled, 170mmbbls

Phase 2 12 wells, 149mmbbls

Phase 3 16 wells, 95mmbbls

Central Area

Phase 1 12 wells, 212 mmbbls

Phase 2 13 wells, 102 mmbbls

· Total barrels developed (all phases) 730 mmbbls

· Phase 1 + Phase 2 peak production rate 55,000 bbls/day, increasing up to 150,000 bbls/day once all phases have been developed

Navitas continues to estimate Capex to first oil on phase 1 of c$1.4 bn and in this regard has entered into a number of FEED agreements including an MOU for an FPSO which is currently operating in the North Sea, along with various agreements relating to the provision of subsea equipment. Navitas's target for FID also remains mid-year 2025.

Navitas published the March 2025 NSAI Independent Report which is available on Navitas' website, and contains the following resource estimates (rounded, for oil only):

\* Totals may not sum precisely due to rounding adjustments

As the project moves further along the path towards FID, Rockhopper intends to commission its own Independent Resource Evaluation which will be published later this year.

Rockhopper holds a 35% working interest in Sea Lion and associated NFB licences and benefits from various loans from Navitas in relation to the development, which are detailed in previous announcements.

Enquiries:

Rockhopper Exploration plcSam Moody - Chief Executive OfficerTel. +44 (0)20 7390 0230 (via Vigo Consulting)

Canaccord Genuity Limited (NOMAD and Joint Broker)Henry Fitzgerald-O'Connor/James Asensio/Charlie HammondTel. +44 (0) 20 7523 8000

Peel Hunt LLP (Joint Broker)Richard Crichton/Georgia Langoulant

Vigo ConsultingPatrick d'Ancona/Ben Simons/Fiona HetheringtonTel. +44 (0) 20 7390 0234

Resource Disclosure

Rockhopper is not an addressee and has not been party to the production of the March 2025 NSAI Independent Report. The March 2025 NSAI Independent Report has been produced to PRMS standards. Rockhopper's technical team which includes Lucy Williams (BSc Geology, MSc Petroleum Geology, Chartered Geologist) has reviewed the content of this announcement but has not had opportunity to review the March 2025 NSAI Independent Report, although has confidence in the experience and suitability of NSAI to produce such an independent report.

The last independent resource report commissioned directly by Rockhopper was the ERCE 2016 Report which had an estimated 2C value of 517 mmbbls.