The NTSB report provides a significant amount of information:
Prior to the flight the pilot gave each passenger a personal flotation device (PFD), and briefed them on its use. The fourth/fatal passenger was seated in the aft cargo compartment atop kayak spray-skirts and gloves. The pilot and all four passengers survived the water impact with a few minor injuries. After the impact, the five survivors climbed onto the fuselage top and wings. The pilot and fatal passenger exited the airplane, leaving their PFD's behind. The other three passengers were wearing their PFD's when the accident occurred, and exited the airplane wearing them. The airplane was sinking, and all the survivors swam to a large, nearby iceberg, but were unable to climb out of the water onto the iceberg. The pilot, and the three passengers wearing PFD's, swam back to the airplane, and climbed out of the water onto the airplane. The pilot borrowed a PFD from one of the passengers, and swam back to the remaining passenger, but was unable to render aid because he'd lost all feeling in his hands due to the cold water. The remaining passenger, without aid of a PFD, slipped below the surface of the lake, and was not seen again. The survivors were able to cut through the fabric fuselage skin to retrieve extra clothing from the baggage compartment, which they gave to the pilot who, according to them, was showing signs of hypothermia. During the accident scenario, two of the passengers were dressed in layered clothing, including fleece, as suggested by the pilot. The other two passengers and the pilot were dressed in cotton levis and cotton shirts. As the airplane continued to slowly sink, two of the passengers swam to a smaller ice cake, which they were able to climb on, and the remaining passenger followed. Prior to the airplane sinking, using an inflated dry-bag, the pilot joined the others on the iceberg.
Full report
is available here