Discovery Island is an Island that is still there in the middle of bay lake. If you take the boat over to the Wilderness Lodge or Fort Wilderness you can still see it. This attraction was a precursor to the Animal Kingdom and has been closed since 1999. When it was open, a boat would take you over to the island where you could walk among trails and see different types of birds and wildlife.
River Country was the first water park at Walt Disney World and you can still see it when you take the boat over to Fort Wilderness. The water park opened in 1976 and closed in 2001. Many people say the reason for it closing was because of a new Florida State law that forced all water parks in the state to use municipal water as opposed to water from a lake (which was the source of water for River Country). This actually is not a state law in Florida and the most plausible cause for it closing is that Disney had two other water parks that were much more successful and with tourism down because of 9/11, they had to economical reason to reopen the park.