Spillway, Monte da Rocha Dam, near Ourique, Portugal (© André Gonçalves/SuperStock)

【March 5 2014】Most of the time, the bell-mouth spillway of the Monte da Rocha Dam in southern Portugal looks like this. But when the water in the reservoir gets too high, this drain keeps the dam from flooding the plains in the surrounding countryside. When a circular spillway is draining, it can look like a whirlpool in the sea.Explore breathtaking Gallery from the HuluTrip homepage over the past 5 years..