When you are in the sea area you must swim to a building in the sea. 
When you go in there is a cage with two fish in it. Go get some fish for 
them. When you trow a fish in, one of them eats the fish. When you give 
both fish ten other fishes you receive a mask from the guy how standing 
there. Put on the mask and go to the paradise of spiders on the beach. 
Go in and all the spiders are coming to you and you get the Mask of Thruth.