Monga Bay Kids' Site
Aims to help children learn about rainforests and the environment.
National Marine Mammal Association
On whales and other marine mammals.
Nature Challenge for Kids
Kids' section of the David Suzuki Foundation, dealing with environmental matters.
Skelton Grange Environment Centre
Environmental education for children and young. Though the site says itĺs for children living in West Yorkshire, most of the information is applicable to everyone.
TIME for kids, Earth Day
News, games, quizzes and information on environmental issues.
Has separate sections for young people and children on environmental issues. Part of UNEP.