Ulong Channel is a drift, reef and wall dive in Koror, Palau, in the Philippine Sea. It cuts as an underwater canyon through the western barrier reef, described as one of Palau's most unique diving experiences. A Koror State Rock Island/Dive Permit is required, costing $50 per person and valid for 10 days. Grey reef sharks, reef fish and whitetip reef sharks are resident, with rays and schooling fish occasionally seen. Big reef fish are seen seasonally, from April to July.