Stóra Víti
The Stóra Víti crater at Krafla caldera is one of two craters called Víti, which means hell. The other one is at the famous stratovolcano Askja. Stóra Víti was formed by a steam explosion in 1724 during the Mývatnseldar (Mývatn Fires). Along its rim two areas of hydrothermal activity can be found.
One of the thermal areas is called Twin Lakes and located east of the crater. Coming from the parking lot you have to finish half of the trail around the lake to get there.
Main feature of Twin Lakes Group is a clear, bright blue pool of moderate temperature. Initially consisting of two pools (hence the name), it was formed by the Mývatn Fires and known for spouting mud up to 10 m (33 feet) high. Around 1900 the two springs merged into one.
Also noticeable is a small sizzling hot spring, emitting muddy water.
Behind the north rim of Stóra Víti another thermal area can be seen, which consits of fumaroles only.