The Capillas de Marmol (the Marble Caves), also known as Catedral de Marmol (the Marble Cathedral), is an inredible natural attraction that draws hundreds of visitors every year to the little town of Puerto Tranquilo (from where boats and kayaks can be rented with which to visit). Created by the erosive effect of the blue water of Lago General Carrera lapping at the stone, the Cathedral looks like a beautiful piece of sculpted artwork.