Umi-no-Mori Park, Metropolitan park in Tokyo Bay, Japan

Umi-no-Mori Park is a metropolitan park on 88 hectares of reclaimed land in Tokyo Bay, in Koto City. It sits on a landfill built between 1973 and 1987 from 12.3 million tonnes of waste and construction soil, layered in a sandwich structure. A 1.5-metre layer of planting soil mixed with compost covers the 30-metre waste mound. The park has two small hills, a central lawn and woodland, and the Sea Forest Waterway.

The site was created between 1973 and 1987 by alternating layers of 12.3 million tonnes of waste and construction soil in a sandwich structure. The park concept was approved by the Tokyo Port Council on 24 February 2005, and planting began in 2007. The water sports area opened on 1 June 2019, and the entire park fully opened on 28 March 2025.

The name Umi-no-Mori means "Sea Forest". The park's compost is made from pruned branches and leaves collected from street trees across Tokyo, part of a resource-recycling forest plan. Volunteers and children's ranger groups help tend the wind forest, where seasonal nature observation takes place.

Access is by Toei bus line Ha 01 from Tokyo Teleport, Tokyo International Cruise Terminal or Telecom Center stations, getting off at Umi-no-Mori Park. From July 1, 2025 to March 31, 2026, a free autonomous bus demonstration runs between Shinkiba Station and the park, excluding New Year holidays. The grounds are large, so plan for walking between areas.

The park's compost comes from pruned branches and leaves collected from street trees across Tokyo, closing a resource loop. The site also hosted equestrian and canoe sprint events during the 2020 Tokyo Olympics, and the Sea Forest Waterway opened there in 2019.