3) Mendenhall Ice Caves – Alaska The ice caves are located under the 12 mile long mendenhall glacier located near Juneau. They are only accessible to those willing to kayak to and then ice climb over the glacier.Unfortunately, this wonder is retreating due to global warming and one cave has already collapsed. Loading…
3.Underground natural springs in Mexico. Loading…
The compass Ancient mariners navigated by the stars, but that method didn’t work during the day or on cloudy nights, and so it was unsafe to voyage far from land. The Chinese invented the first compass sometime between the 9th and 11th century; it was made of lodestone, a naturally-magnetized iron ore, the attractive properties […]
