California State Parks: Official website of the California state park system, with links to campgrounds as well as information on the park services

Frank Mundus Fishing: Shark Fisherman

Geocaching.com: Includes large database on caches to hunt down, along with general information on geocaching. Enables to hide and seek a cache, find a benchmark or trackable items

Geotech: Features magazine articles with projects and schematics to build frequency-shift, induction balance and pulse induction metal detectors, coils and probes. Includes articles about the history of detectors, links to manufacturers, and reference sources

Letterboxing North America: US-based portal offering FAQ, links, forums, and a members-only section where clues can be submitted

National Speleological Society: The national caving organization of the USA, with links to all affiliated regions, grottos (clubs), sections, and special interest groups

Off-road.com: Online off-road magazine covering ATVs, Dirt Bikes and 4x4s. Searchable back issues

Save Our Seas Foundation: Awareness, protection, preservation and conservation of the global marine environment are the heart of the Save Our Seas Foundation's mission. Save our Seas Foundation is a non-profit making Swiss foundation headquartered in Geneva, Switzerland

The Rebreather web site: Dedicated to the dissemination of information regarding the art and science of diving rebreathers of all types

The Virtual Cave: A wide-ranging introduction to the geology of caves. Organised by geological feature with pictures and clickable virtual maps

Washington State Parks and Recreation Commission: Official site has campsite listings and reservations, maps and parks information and schedules