Weh Island or Pulau Weh or Pulo Weh is a small active volcanic island to the northwest of Sumatra, 45 minutes by fast regular ship or 2 hours by ferry from mainland, Banda Aceh. It was originally connected to the Sumatran mainland and became separated by sea after the volcano's last eruption in the Pleistocene era. The island is situated in the Andaman Sea. The largest city on the island, Sabang, is the northernmost outpost of Indonesia
The island is known for its ecosystem; the Indonesian government has declared 60 square kilometres (23 sq mi) of inland and sea around the island as a wildlife protection area. A rare megamouth shark species was found on shore and the island is the only habitat for the threatened toad, Bufo valhallae (genus Bufo). Coral reef areas around the island are known for their large variety of fish species.
Weh Island is located in the Andaman Sea, where two groups of islands, the Nicobar Islands and Andaman Islands, are scattered in one line from Sumatra to the north up to the Burma plate. The Andaman Sea lies on an active moving small tectonic plate (microplate). A complex geological fault system and volcanic arc islands have been created along the length of the sea by the movement of the microplate. The island lies about 15 kilometres (9 mi) off the northernmost tip of Sumatra. The island is small at only 156.3 square kilometres (60.3 sq mi), but mountainous. The highest peak is a fumarolic volcano, 617 metres (2,024 ft) high. The last known eruption is estimated to have occurred in the Pleistocene age, as a result which the mountain partially collapsed and was filled by the sea, forming a separate island.
The economy on Weh Island is dominated by agriculture. The main products are cloves and coconuts. Small-scale fisheries operate in the area, and fishermen have used explosives and cyanide fishing extensively. Therefore since 1982, a wildlife protection area (suaka alam) has been declared by the Indonesian government that includes 34 square kilometres (13 sq mi) inland and 26 square kilometres (10 sq mi) of surrounding sea.