Hidden inside the caldera, a mile below the summit, sits a lake the colour of the sea and a set of hot springs that feel like a reward for every step it takes to reach them. This is the quiet heart of Mount Rinjani.
Ask our guides which part of Rinjani they'd go back for, and plenty of them won't say the summit — they'll say Segara Anak. After the cold, lung-burning push to the top, dropping down into the caldera to a huge blue-green lake, with steam curling off hot springs at its edge, is one of those moments that stays with you long after your legs have recovered.
Segara Anak is the crater lake that fills part of Rinjani's vast caldera, sitting at roughly 2,000 metres — well below the 3,726-metre summit that looms over it. The name means "child of the sea" in the local Sasak language, and once you see the colour of the water you understand why: a deep, oceanic blue-green ringed by black volcanic walls.
Rising straight out of the lake is Gunung Barujari, a small, still-active cone born from eruptions within the caldera. It's a reminder that Rinjani is very much a living volcano — the whole lake sits inside the crater left by an enormous eruption centuries ago.
A short walk from the lakeshore, natural hot springs called Aik Kalak tumble down the rocks, heated by the volcano beneath your feet. After a long day on the trail there's nothing quite like lowering yourself into the warm water and letting your shoulders drop. Local people have long believed the mineral water has healing properties, and whether or not that's true, tired muscles certainly seem to agree.
It's a social, unhurried place — trekkers from different groups end up sharing the pools, swapping stories about the summit while the steam drifts up into the cold mountain air.
Segara Anak isn't just scenery. For the Sasak — the indigenous people of Lombok — and for Balinese Hindus, Rinjani and its lake are sacred. Pilgrims come to the water to pray and to leave offerings, and a ceremony called Mulang Pekelem sees offerings cast into the lake. Trekking here is a privilege, and we ask everyone to treat the place with the respect the local community gives it.
On the 3D2N route you'll typically descend to Segara Anak on the second day, after the summit push and breakfast at the rim camp. The path down into the caldera is steep and rocky in places, and the climb back out the far side toward Senaru is a genuine effort — this is a big mountain, and there are no shortcuts. But camping a night by the water, falling asleep to the sound of the lake and waking with the crater walls glowing at dawn, is worth every metre.
If you have the time, yes — without hesitation. The summit is the trophy, but Segara Anak is the soul of the trek: quieter, warmer, and the part people describe most vividly years later. If your schedule only allows the 2D1N, you'll still have an incredible summit sunrise. But if you can spare the extra day and night, the crater lake is what turns a hard climb into a story you'll tell for the rest of your life.
New to planning all this? Start with our complete Mount Rinjani trekking guide, or read about what the summit push is really like.