Sangihe — Banua Wuhu

Diving Sangihe means committing to a boat for the whole trip. Charters are put together down in North Sulawesi, usually dive Bunaken or Bangka on the way out, then steam north overnight, so two of the days go to passage rather than reef. Once the boat is up in the chain the rhythm settles into three or four dives a day off tenders, timed by the tide rather than the clock, with the vessel shifting each evening to whichever island offers a lee. Nothing can be walked to, and when a site turns out to be unworkable there is no second option nearby.

The islands are the exposed tops of volcanoes, so the underwater shape is steep almost everywhere: dark rock falling away from a narrow fringing shelf, cut by ridges and sand chutes. What separates one site from the next is exposure. The inner, sheltered sides hold shallow coral and rubble that stay comfortable in most conditions, while outward-facing rock sits in moving water and gets dived as a one-way pass with the boat following bubbles. Guides read the tide before every entry, and a plan can change once the crew has looked at the water.

The signature here is thermal rather than a big-animal encounter. Banua Wuhu is a listed active volcano, credited with throwing up short-lived islands during eruptions in the nineteenth and early twentieth centuries, and the dive over its shallow summit is a slow one spent working out where the ground is venting and where it is simply reef. Around that, the draw is the absence of anyone else: no other boats at a site, and villages rather than resorts along the shore. It suits divers already comfortable being dropped into moving water, travelling without a fixed schedule, and willing to give up two days to passage.