Siayan is one of the Batanes Islands, part of an archipelagic province in the Philippines.

Also known as Ditarem Island in the native language,[1] the island is about 1/2 mile to 3/4 miles in diameter and lies about 5 miles (8.0 km) north-northeastward of Itbayat Island.

There are several detached rocks off Siayan's northeast side, rendering the channel between it and Mabudis unsafe for larger vessels.

[2] Siayan has an elevation of 538 ft (164 m) and is listed as an inactive volcano[3] by the Philippine Institute of Volcanology and Seismology.

This article about a location in Cagayan Valley region is a stub.