Final answer:
The second largest boiling lake in the world is Dominica's Boiling Lake, a true natural wonder caused by rainwater heated by magma, situated in Morne Trois Pitons National Park.
Step-by-step explanation:
The second largest boiling lake in the world is the Boiling Lake located in Dominica, which is situated in Morne Trois Pitons National Park, a World Heritage site. This lake is approximately 200 feet to 250 feet (61 to 76 meters) across and the depth varies.
The boiling water is a result of rainfall seeping through the ground, heated by hot magma beneath the surface. The steam and boiling bubbles make it a true natural wonder to observe, though visitors are cautioned to keep a safe distance due to its extreme temperatures and active conditions.