The first animals to be put on the endangered list, Aldabra tortoises of the Aldabra atoll are the only surviving giant tortoises of the Indian Ocean islands.   Galapagos tortoises are also an endangered species from the Galapagos Islands, located in the Pacific Ocean.   A number of other tortoises and turtles are at risk, as well.  

Further reading:   the Aldabra Tortoise from The Oakland Zoo, there's Turtle Trax, a page devoted to marine turtles, and the Galapagos Tortoise from the people at Discover Galapagos.