Complex sentence: Two others went adrift in the Gulf of Mexico, but they were recovered but one platform, originally located 12 mi (20 km) off the Louisiana coast, has washed up onshore at Dauphin Island, Alabama.
Split into simpler sentences: Two others went adrift in the Gulf of Mexico, but they were recovered. One platform, originally located 12 mi (20 km) off the Louisiana coast, has washed up onshore at Dauphin Island, Alabama.