Daisy Murchie was an outstanding pioneer in open water swimming in America. Murchie swam from Avalon on Catalina Island to Long Beach on the California mainland in 17 hours 4 minutes in 1955 at the age of 39 to become the first woman to cross the Catalina Channel. Murchie also crossed the Catalina Channel in the other direction, swimming from the California mainland to Catalina Island on 2 September 1956 in 15 hours 40 minutes.
She also swam the Salton Sea a few times as promotion for a neighboring city and around Atlantic City with American professional marathon swimmer Tom Park. She also trained in Alamitos Bay (Naples Island) in Long Beach, California with Greta Andersen.