Todoque Cave
I come from Yorkshire and I’m used to limestone caves, so I was surprised when I found that the volcanic island of La Palma has lots of caves too. Volcanic caves are formed when a river of lava solidifies on the top and sides, but the middle (insulated by the solid-but-still-hot lava around it) stays runny. Sometimes big bubbles of gas force their way to the surface, leaving a hole…