This really interesting spider was discovered just outside of Weyburn, Saskatchewan, Canada. The approximate coordinates are 49°39′40″N 103°51′9″W (68 miles north of the US-Canada border. It was discovered early afternoon on Saturday July 14th, 2012 in a box of water. The site has a floating tree nursery with plastic-lined boxes approximately 8 feet by 4 feet. These boxes are filled with water and duckweed is very prolific. The spider was found resurfacing from under the duckweed, floating a while and then diving underneath the duckweed again. I waited a few minutes after it dove, but did not see it resurface again. It measured perhaps 2 inches long.
Any help in identification is greatly appreciated. This website is fantastic by the way!