Anybody who surfs knows there's often plenty of downtime waiting for the perfect swell to come along. So what do you do while you're waiting around? Option 1: Nothing (boo). Option 2: Fabricate your own ready-made waves, via a makeshift current pool hooked up to the Waimea River, one of the longest rivers in the Hawaiian Islands. Kudos to Stephan Figueiredo, Dennis Tihara, Gabriel Pastori, Diego Silva and Felipe Cesarano for their up-and-go-get-'em.
There has been some debate regarding possible ecological damage of mixing and matching the ocean and river water. Here's a couple noteworthy responses via YouTube:
"The lake at Waimea Bay fills up annually and floods the roads upstream due to the hard Winter weather's rains. A river eventually emerges and carries all this dirty water to the ocean. It's a natural process. The water from the river gets carried away overnight by the currents; no ocean fish get? harmed. There are also no fresh water fish harmed because they stay in their natural habitats; all this water is from rains, not an occupied river or lake." -Buddy1479
"Ok before any one rants again, the water is coming from a stream near the beach that backs up with? water every year. The nature of the waves coming in causes the sand to become a natural damn. The people in the video simply linked the backed up stream to the ocean. The little rapids they make only last for an hour and the beach sand recovers in no time at all." -coltleader
Weigh in below.