It is Michael Phelps of the U.S.A.
There is no 50 km swimming event.
The number one most watched summer Olympics sport is soccer. The second most watched sport is men's and women's swimming.
There are 17 Men'a events and 17 Women's events for Swimming
2:15:25 hr:min:sec
1:51:52 hr:min:sec
Park Taehwan (Korea) won the gold medal in the men's 400 meter freestyle swimming in the 2008 Summer Olympics.
Brent HaydenCanada (CAN)
James MagnussenAustralia (AUS)
Sun YangChina (CHN)
Ryan Cochrane Canada (CAN)
Ryosuke IrieJapan (JPN)
Ryosuke IrieJapan (JPN)