Gaua (formerly Santa Maria) is a volcanic island that belongs to the archipelago of the Banks Islands of the Pacific island nation of Vanuatu. It is located near the Santa Maria fault zone. The island has a diameter of 20 km and an area of ​​328.2 km ²; the 797 -meter-high shield volcano is one of the most active volcanoes in the archipelago.

At the summit of the volcano is a 6 times 9 kilometer caldera is 700 meters deep and in which there is a crater lake called Lake Letas has formed. The largest and most active of the intra- caldera volcanoes in this lake is Mount Garat. It is located in the southwestern part of the lake on the shore and extends a bit into him.

Since the end of 2009, the signs of a major eruption in Gaua increase. At times 3,000 islanders were evacuated. Smaller eruptions promoted ash clouds that rose up to 3 km altitude. It also strombolian explosions were observed.