The whales get top billing in every brochure for Vava'u, and they earn it — from July through October, humpbacks migrate up from Antarctica to calve in these sheltered channels, and swim tours here are some of the only ones in the world where you're permitted in the water with them, at a respectful, heavily regulated distance. But the whales are only the loudest reason to come. The quieter one is that Vava'u is what people mean when they say "island time" and don't just mean slow service.

There are sixty-one islands in the group, most uninhabited, and a single town, Neiafu, that wraps around a harbor so deep and sheltered that sailors call it the Port of Refuge. It has one main road, a produce market that runs out of most things by ten in the morning, and a general unhurried agreement that nothing is really urgent.

I chartered a small boat for three days with a Tongan captain named Sione who navigated by landmarks I couldn't see and stopped, unbidden, at a blowhole formation on 'Eueiki that wasn't on any map I'd looked at. We anchored most afternoons over reef flats in eight feet of impossibly clear water, snorkeling among giant clams the size of car tires, their mantles an electric blue-green that looks almost synthetic until you touch the shell and it's real, cold, ancient rock.

Swimming Beach on Kapa Island — actual name, no imagination required — has a sea cave you can free-dive into and surface inside a hidden grotto lit by a hole in the rock above, the water glowing turquoise from underneath. I went in alone at low tide and stayed until my fingers wrinkled, mostly because I didn't believe I'd get the light again.

Evenings in Neiafu mean feasting on 'ota 'ika, Tongan-style raw fish in coconut cream and lime, at a waterfront table while the fishing boats come in, and turning in early because there's genuinely nothing else to do after nine — which, a week in, starts to feel less like a limitation and more like the entire point.

Getting there: Fly from Tongatapu to Vava'u's Lupepau'u airport; onward inter-island transfers to smaller resorts are usually by boat.

Best months: July through October for whale season; the weather is drier and cooler too.