You can do a lot of things in 30 minutes, but they’re probably not as fun as surfing the same wave with a boatload of your buddies. Distance-wise, that’s about 20 minutes…on the same wave! The tidal bore phenomenon known locally as the Pororoca, an indigenous word meaning ‘Great Noise’ or ‘Destroyer’ occurs during the Lunar Equinox in the rainy season, producing a tidal bore wave over two meters high and miles wide, washing back inland for as much as 30 miles or more.
Since 1999, an annual championship has been held in São Domingos do Capim (on the adjacent Guamá River) in the Amazon Region of Brazil to see who can ride the tidal bore wave the longest. Apparently surfing the Pororoca is a bit dicey , as the water contains a significant amount of debris from the shores of the river (often entire trees), in addition to the odd crocodile or sometimes (rarely) those spiny-like fish called ‘Candiru’ that are attracted to the smell of urine and have been known to swim into the urethra of a penis and have to be surgically removed.*
In 2003 the Brazilian Picuruta Salazar won the event with a record ride of 12.5 km lasting 37 minutes. Current tidal bore world record holder Serginho Laus has been known to surf the longest continual wave on Earth for more than 45 minutes.
*The first documented case of the removal of a candiru from a human urethra did not occur until 1997, and even that incident has remained a matter of controversy. Source-Wikipedia.