The Lost River Delta is a themed, "Land" in Tokyo DisneySea.
The Lost River Delta is set in Cusco, Peru and is themed to being the remains of an ancient mesoamerican region that has been reclaimed by nature over the centuries.
The Daily Gnus newspaper in Disneyland's Adventureland mentioned the Lost River Delta as having been a host to the Adventure Trading Company. This same article also mentions the other locations to have done so as having been Mystic Point and Harambe.
The primary feature of the Lost River Delta is the Temple of the Crystal Skull. This temple was excavated in 1931 by the joined efforts of Indiana Jones and the League of Adventurers in search of the Fountain of Youth. The league would be chased out from the temple and Indiana trapped within, both by the temple's spirit the Crystal Skull. Jones' accomplice Paco would go on to hold tours of the temple for additional revenue and eyes able to look for Jones though these guests would become targets of the Crystal Skull. Indiana would assist in saving these guests and all of them would escape the temple.
A letter from the delta is addressed to Rosita in the Enchanted Tiki Room, posted on the board in the Skipper Canteen. In the library is a series of books by Paco which detail the Temple of the Crystal Skull.
At some point in time during the 19th century, S.E.A.-member Harrison Hightower III and his manservant Archibald Smelding would travel to the Lost River Delta. They'd come upon a 5000 year-old sacred site dedicated to the god of fire and the god of water. Hightower and Smelding would seize the water god idol's head to put on display in Hotel Hightower, New York for his collection. At some point circa 1931, a restoration team connected to the Cantera El Barranca Rocoso excavation team attempted to restore the stolen idol to its original position but made the mistake of having the water-god and fire-god face one another. As a result, the temple spirits were angered and caused the mine carts of the team to run out of control.
- While a real-life location, the setting of Cusco, Peru might be a tribute to Emperor Kuzco from the 2000 Disney animated film The Emperor's New Groove as Raging Spirit's facade was inspired by the design of Kuzco's palace in this film.