Tofua and Kao

West of Ha'apai's coral flats, two volcanoes stand out of deep water like a diagram of the Pacific's engine: Tofua, a broad caldera island whose crater holds a freshwater lake and steaming vents that still smoke; and Kao beside it, a 1,046-metre cone so perfectly drawn it looks designed - Tonga's highest point. History gives them a cameo: it was off Tofua in 1789 that the Bounty's mutineers set Captain Bligh adrift, and his epic open-boat voyage began at this shoreline. Today the visit is expedition-flavoured - boat charters from Pangai, a steep scramble to Tofua's rim, camps under sky-fields of stars - for travellers who like their islands unedited.

What you actually see

• Tofua's caldera - the crater lake and smoking vents from the rim.
• Kao's cone - the kingdom's highest point drawn perfect against the sky.
• The Bligh shoreline - where the Bounty story turned.
• The open-ocean crossing - Ha'apai's wild west by small boat.

When to go

May to October for the most settled seas - the crossing is the gatekeeper, and charters wait on weather in any month. Rim camps want gear for wind and rain regardless of forecast.

Honest expectations

This is a genuine mini-expedition: open-water boat legs, a steep loose ascent, no facilities whatsoever and self-carried everything - arranged through Pangai operators with real weather margins. Volcanic activity varies; guides' judgement rules. The reward is a raw Pacific volcano with witnesses in single digits.

Nearby

Pangai and the Ha'apai atolls, and the whale channels between.