Ice diving
Ice diving is a type of penetration diving where the dive takes place under ice. Because diving under ice places the diver in an overhead environment typically with only a single entry/exit point, it is considered an advanced type of diving requiring special training (although whether it constitutes technical diving is part of a wider debate within the diving community). Ice divers are generally tethered for safety. This means that the diver wears a special harness under the scuba unit. A line is secured to this harness, and the other end of the line is secured above the surface by one of a number of methods.