Up on the rim of the Batur caldera, the air is cool, the light is sharp, and below you lies a landscape that looks like nowhere else on Bali. The caldera is a huge bowl, about ten kilometres across, formed by a massive eruption tens of thousands of years ago, and inside it rises Mount Batur, a younger volcano with black lava flows spreading down its flanks, and beside it Lake Batur, a crescent of deep blue water. Mount Batur is still active, with eruptions in the twentieth century, and the lava fields from those eruptions are still bare and black.
The lake is sacred to the Balinese, who regard it as the source of water for the island's rice terraces, and the temple of Pura Ulun Danu Batur on the rim is one of the most important on Bali, dedicated to the goddess of the lake. On the far shore lies Trunyan, a village of the Bali Aga, the island's original inhabitants who predate the Hindu kingdoms. Their customs differ from the rest of Bali; most famously, instead of cremating or burying their dead, they lay them out in the open under a large tree, said to neutralise the smell. The village can be reached by boat from the shore, though the experience can feel commercialised.
Many visitors climb Mount Batur before dawn to watch the sunrise from the summit, with views over the caldera and across to Mount Agung and Mount Rinjani on Lombok. The trek takes a couple of hours and is popular, so do not expect solitude. Around the lake, hot springs offer a chance to soak, and the farms on the caldera floor grow onions, chillies and other vegetables in the volcanic soil.
The roads here are steep and winding, with tight bends down to the lake and back up to the rim. The surface is often rough and the gradients severe, so take care, especially on the descent. The rim road through Kintamani and Penelokan has fuel, restaurants with views and many hawkers. The area is also known for coffee and citrus, which grow on the slopes. The weather can be cool and misty, especially in the rainy season, so bring a jacket. Early morning and late afternoon give the clearest views and the kindest light over the lake.