Boulder caves are not usually tourist attractions.  These caves are different from some caves, they form in two different ways.  There first way of forming is is that a cliff falls on top of each other, they leave tunnels that bury deep into the rock, forming what you call caves.  Another way they form is that huge pieces of ice carrying debre like trees crash into the face of cliffs.  This causes huge rocks to fall and rest on the cold ice.  As spring goes by the ice melts and it sinks to the ground, slowly forming a cave of massive rocks.  Boulder caves are very rare. They are also very hard to enter.  Geologists are very interested in these caves because they are very, very rare.