Lost Lake, located in central Oregon, is known for rapidly draining every year through a six-foot (two-meter) wide hole in the lake's bottom (as shown in the video). Early in the following spring, however, the lake fills up again, as snowmelt from the surrounding mountains accumulates faster than water can drain out through the hole. That hole is really a lava tube - a geologic feature made when lava cools around the edges of a river of molten rock. After the hot lava drains away, it can leave an empty space. ...

Lake Baikal in eastern Siberia is the oldest freshwater lake on Earth, and one of the largest and deepest, containing around one-fifth of the world's freshwater. In winter, it freezes over, and these beautiful transparent, turquoise masses of broken ice appear momentarily in March, caused by the unequal structure, temperature and pressure in the main body of the packed ice.

Described as the first “truly feasible” contraption to reduce ocean plastic, this little wheel has been clearing rubbish out of Baltimore's harbour since May.