In the rivers of Hawaii lives a small fish called the rock-climbing goby. It is smaller than your finger. But this little fish does something amazing: it climbs waterfalls.
The goby is born in the river, high in the mountains. After it hatches, the water carries the baby fish down to the sea. When it is bigger, it must return to the calm water high up the mountain. There is only one way: up. The goby holds the wet rock with its mouth, which works like a small suction cup. It also has a second sucker on its belly. Mouth, belly, mouth, belly. Centimetre by centimetre, it climbs straight up the rock behind the falling water.
Some of these waterfalls are taller than a twenty-storey building. For a fish this small, that is like a person climbing a mountain many kilometres high. The goby does not hurry. It just never stops.
