Every winter, as many of us are shoveling mounds of snow off our driveways so we can return to our monotonous jobs, a select few are enjoying the beach and showing off their beautifully tanned bodies. Is this for real, you ask? And if so, where is this magical place? Hawaii, of course. 
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On the North Shore of Oahu is the picturesque Waimea Bay at the mouth of the Waimea River. Waimea Bay in the winter can see waves up to 30 feet high, and that's just the back side of the wave; the front side can actually double in size, notes best-of-oahu.com. With waves that large, it's no wonder surfing Waimea Bay is considered a rite of passage for surfers from all over the globe. However, waiting for the perfect wave can mean a lot of downtime, so surfers have a couple options: Wait it out, or be resourceful. When competitions are in full swing, the latter tends to be the more popular choice.

Waimea Valley conservationists teamed up with Jamie O'Brien and other local surf luminaries to build a man-made trench at the river's mouth. After hours of digging, not only had they helped the land by preventing flooding, but the surfers also took advantage of the waves the trench helped create well into the night. (Check out the making-waves video below.)

How does the trench create waves?

The high surf beating down on the beach compresses the sand into a naturally formed dam, barricading the water flow of the river. Harsh weather conditions, including incessant rain, create an overabundance of water in the river. With such an excessive amount of water trapped behind the dam, Waimea River builds up pressure until it is either released or forced to overflow into the surrounding valley. Digging the trench relieves the pressure from the river into a surfable stream. 

How does this affect the ecological system of both Waimea Bay and Waimea River?

Every year, the nine-mile Waimea River overflows right past the town and into the bay, with or without human intervention. Building the trenches is the surfers' way of assisting Mother Nature. Luckily, this is neither illegal nor damaging to the environment — simply a fun way for the surfers to shred some gnarly waves. 

Surf's up, brah!