OUTSIDE 2: Outdoor swimming as a nature-based intervention for depression: a full-scale randomised control trial

Major depression is common and existing treatments show only modest effectiveness and acceptability, highlighting the need for accessible, engaging and potentially more cost‑effective alternatives. Although outdoor swimming has shown promise, there is a lack of rigorous large‑scale trials evaluating its clinical impact and economic value.

This study addresses these gaps through a pragmatic, multi‑site randomised controlled trial comparing an eight‑session outdoor swimming intervention plus usual care with usual care alone in adults with major depression. A central focus is to determine both clinical outcomes and cost‑effectiveness, establishing whether this approach offers a safe, scalable and economically viable intervention that could improve outcomes while reducing healthcare costs.

Funder: NIHR