Dziani Dzaha

Petite-Terre's volcanic origins sit in plain view at Dziani Dzaha: a crater lake of startling green - algae and sulphur chemistry doing the tinting - held in a perfectly round bowl whose rim walks in an easy hour, ylang and scrub on the slopes, and the contrast doing the photography: emerald lake inside the ring, sapphire lagoon outside it, the reef line drawing white between blues. Legend populates the lake generously and swimming is traditionally avoided (the chemistry agrees); the visit is the loop, the light and the lookout benches where Mayotte's double-blue geography explains itself at a glance.

What you actually see

• The green lake - the sulphur-and-algae emerald in its bowl.
• The rim loop - the hour's walk around the crater ring.
• The double-blue contrast - lagoon and reef beyond the crater lip.
• The ylang slopes - perfume scrub on the volcanic ring.

When to go

May to October, the dry austral winter, keeps the rim path firm and the light clean; early morning beats the heat on the shadeless ring and gilds both blues.

Honest expectations

The loop is short, hot and shadeless - water and hats even for the hour; the lake itself is for looking, not swimming, by both custom and chemistry. Petite-Terre logistics are easy (it is the airport island); combine with the Badamiers spit and vasiere birdlife for the half day.

Nearby

The Badamiers mudflats, Dzaoudzi's rock and the barge to Grande-Terre.