The tunnel, one of the most unique dives in Palau, is considered to be an advanced dive - for two reasons: depth, and the overhead environment. Situated on the western side of the atoll, the vertical wall juts out into the Philippine Sea, forming a pointed corner where a large (50 foot high) tunnel cuts right through the wall. The bottom is well below 140+ feet (40+m). Because of the depth, time in the tunnel is restricted to around 12 minutes, but getting there and back is exciting in itself. Dropping down over the wall, you will enter a horizontal tunnel beginning at a depth of 90 feet (27m). As you enter the tunnel, there is a window on your left looking out to open sea, and the exit is straight in front of you. White tip sharks can be seen sleeping on the sandy bottom, which gets as shallow as 110 feet (33m) and swirling schools of bigeye trevally are common here. Inside the tunnel is home to some of Palau's rarer fish: colin’s angelfish, decorated dartfish, helfrich’s dartfish, and burgess’s butterfly fish - all oriented to the roof of the cave and swimming upside down. This is one dive where you will definitely need to carry a flashlight.