OES-Environmental (formerly known as Annex IV) is an international programme, run by the US Dept of Energy and implemented by the Pacific Northwest National Laboratory (PNNL) in Washington, USA. The programme examines the environmental effects of marine renewable energy (MRE) development.

OES-Environmental mobilises information and practitioners from OES (Ocean Energy Systems) nations to coordinate research that can progress the industry in an environmentally responsible manner. A key component of this effort involves making existing information available and accessible.

Links to a number of outputs from OES-Environmental are included here. These include the Tethys Knowledge Base and the recently published 2020 State of the Science report.