Tofua is a volcanic island in Tonga, about 100 miles (161 kilometers) north of the main island. Its sides rise steeply to the rim of its caldera, which is partially filled by a crater lake roughly 1,600 feet (500 meters) deep. The entire island is a national park, containing many species of unique birds and the largest area of undisturbed Tongan tropical moist forests in Tonga.—-19.750000°, -175.075000°