One of the largest blue holes on Espiritu Santo and it is indeed deep blue in color. Blue holes are a natural phenomenon and are common to the island, though this one in particular leads to the ocean and you can come through here by kayaking from Oyster Bay. The Entrance fee is 500 Vatu, which is about $5. You have to at least visit one blue hole in your time in Vanuatu, Espiritu Santo has the best of them.
