The name tells you most of it. Lava Lake exists because a flow of molten rock once dammed the valley, trapping the spring water and snowmelt that seeped through the volcanic ground. It sits at about forty-eight hundred feet on the Cascade Lakes Scenic Byway, ringed by pine forest, with the Three Sisters visible on a clear day. Right beside it is Little Lava Lake, which is the headwaters of the Deschutes River, one of the best-known rivers in Oregon, and a quiet spring that gives birth to a major waterway.
The ground here is porous. Rain and snow sink into the lava rock and emerge as springs, which is why the Deschutes starts as such a steady, cold stream rather than a flashy mountain torrent. The surrounding forest is lodgepole and ponderosa pine, and in the meadows near the edges you may see elk and deer. Birds are easy to watch, from ospreys fishing in the lake to waterfowl on the shallows, and the quiet is broken mostly by wind and the occasional boat.
The byway here is a gentle, well-surfaced road, without the intensity of the section near Mount Bachelor. The curves are easy, the gradients mild, and the traffic usually light. It is a good place to relax on a bike, enjoy the mountain air, and take your time. The season is short: heavy snow closes the high section of the byway in winter, and ice can linger into May. Summer afternoons can bring thunderstorms, and the temperatures drop quickly after dark even in August.
Bend, a good thirty-odd kilometres to the east, has the stations, restaurants, and shops, and Sunriver and Three Rivers are smaller settlements closer by. Bring snacks and water, and keep a spare layer in the pannier. Mosquitoes in early summer can be fierce, and the lake is cold enough to discourage all but the hardiest swimmers. The best time of day is early morning, when the lake is calm and the reflections are sharp.