This is a fantastic swim through Istanbul, in the Bosphorus. Once a year, in July, this major shipping channel - a boiling mass of water - is shut for an annual swimming race, during which around 1000 swimmers plunge in and swim from Asia to Europe. Huge tankers are held up at either end of the 6.5km course waiting for the swimmers to complete the course.
There is a major current - take all the advice you can get from other swimmers about avoiding eddies around island, and when to start heading towards the finish line to avoid being swept right past it - and you swim under two of Istanbul's huge landmark bridges
Sign up through the Turkish website: http://www.bosphorus.cc/
A great way to enjoy a weekend in Istanbul. Swimmers gather, change, get ferries upstream, then jump in like lemmings.
This is a crowd-sourced map. Abilities vary, and conditions change. Always assess risks for yourself before getting in.
Strong and conflicted currents.