The bay consists of a dense cluster of over 3,000[citation needed] limestone monolithic islands each topped with thick jungle vegetation, rising spectacularly from the ocean. Several of the islands are hollow, with enormous caves. Hang Đầu Gỗ (Wooden stakes cave) is the largest grotto in the Hạ Long area. French tourists visited in the late 19th century, and named the cave Grotte des Merveilles. Its three large chambers contain large numerous stalactites and stalagmites (as well as 19th century French graffiti). There are two bigger islands, Tuần Châu and Cat Ba, that have permanent inhabitants, as well as tourist facilities including hotels and beaches. There are a number of beautiful beaches on the smaller islands.