From Bulbapedia, the community-driven Pokémon encyclopedia.
Wazoo Island (Japanese: ワズワ島 Wazuwa Island) is an anime-exclusive location in Hoenn, found between Lilycove City and Mossdeep City. It was featured in The Relicanth Really Can!.
The island's beaches, crystal-blue waters, and Grand Wazoo Resort make it a popular tourist destination. A deep ocean and sea trenches surround Wazoo Island, and are home to a school of Relicanth.
Adam and Evelyn, a married couple, live on the island. They own a salvage shop called Bounty of the Sea, and Adam is an underwater treasure hunter while Evelyn examines the items he finds for value.
According to legends, 100 years ago, the King Neptune, a cargo ship carrying the greatest treasure ever, was caught in a typhoon and sank near Wazoo Island. Ash and his friends offered to help Adam find the infamous shipwreck, and after their submarine became caught in a rip, they found it in an underwater cavern. The treasure was eventually revealed to be Green Shards, which were valuable 100 years ago, but not today.