Kintamani, the central highlands
Bali's interior is volcanic, and nowhere is that plainer than at Kintamani, where the road climbs out of the paddies onto the rim of a vast ancient caldera and the ground falls away to reveal Mount Batur rising from the floor, a dark, perfect cone with a crescent of lake at its foot and the lava fields of its last eruptions still black across the plain. At 5,633 feet it is not Bali's highest peak, that honor belongs to Mount Agung to the east, but it is the one you can climb before breakfast, and the classic way to do it is in the dark.
The trek begins around 4am from the village below the mountain, headlamps bobbing up a trail of volcanic sand and loose rock. It is steep in places and takes most people about two hours, with a few scrambling sections near the top, and then you are on the rim as the sky turns from black to violet to orange. The view from up here is the whole of eastern Bali at once: the lake silvering below, the ridges of the caldera, Agung's shadow on the horizon and, on a clear morning, Mount Rinjani on Lombok far across the strait. Your guide cooks eggs in the steam of a volcanic vent while you watch, and the macaques arrive to inspect the breakfast.
The descent in daylight shows you what you climbed, a moonscape of cinder and old lava, and the morning finishes with a soak in the natural hot springs at Toya Bungkah on the lakeshore, warm mineral pools right at the water's edge, then coffee on the rim at Kintamani. It is an early, physical morning, so we schedule it from Ubud or the highlands rather than the coast, with a licensed local guide, a private driver waiting at the bottom and a slow afternoon planned after.