On 8/17/95 three openwater divers drowned at Temple of Doom. They were in a party of eight and being lead by a DIVEMASTER, from Cozumel, who was NOT CAVE CERTIFIED. After a short cavern tour the party proceeded straight down the Madonna Passage. They passed this very warning sign with the grim reaper on it. In other words they went BEYOND THE CAVERN ZONE! It seems that they had no navigational problems but rather extended their stay in the cave for more than half their air supply before attempting to exit. They continued deeper into the cave until one by one, realizing their dire predicament, they turned to exit. Three of them didn't make it out. The fleeing party discovered two of their comrades already dead and a third woman, who had also broken from the group, swimming out. Apparently she was very low on air. She never made it. On the surface the divemaster, who was out of air, swapped tanks with the womans husband, who had some air left. He was able to get the woman out but she was in critical condition and she died a few hours later.