On November 19, 1994, at 1519 Alaska standard time, a wheel equipped Cessna Model 185F airplane, N9618H, registered to the pilot-in-command, nosed over during a landing attempt on the frozen over Lake Hood Seaplane base, Anchorage, Alaska. The private certificated pilot, the sole occupant, was not injured and the airplane sustained substantial damage. The 14 CFR Part 91 pleasure flight last departed the Merrill Field Airport in North Anchorage, Alaska and the destination was Lake Hood. Visual meteorological conditions prevailed and there was no flight plan on file for the flight. The pilot was planning to land on the ice covered lake to exchange his landing gear wheels for ski equipment. While inbound to Lake Hood, the pilot was advised by Anchorage Air Traffic Control Tower personnel that a NOTAM was in effect for Lake Hood and the airport was closed. The pilot continued with the approach/landing. The plane touched down in soft slushy ice/snow and nosed over. The airport/facility directory indicates that overflows onto the ice may occur during the winter months.