HMCS Florence was a commissioned patrol boat of the Royal Canadian Navy (RCN) that served in the First World War. Originally launched as the yacht Czarina, she was acquired by John Craig Eaton in 1910 and renamed Florence. Following the outbreak of war, Eaton donated the yacht to the RCN, which commissioned her as HMCS Florence in July 1915. She spent most of her service career as a guard ship at St. John, New Brunswick and patrolling in the Bay of Fundy, but proved unsuitable for navy work and was paid off in September 1916. Subsequently sold to buyers in Martinique, Florence was reportedly lost in the Caribbean in January 1917.