Hawaii has some of the most varied beaches in the world — white sand, black sand, red sand, and even green sand beaches, the result of different volcanic minerals and coral compositions. Each island has its own character. Oahu's beaches are the most accessible and the most crowded; Kauai's are the most dramatic; the Big Island has the greatest variety; Maui balances all of the above. All beaches in Hawaii are public by law — no private beaches. The ocean is warm year-round (around 24–27°C) but can have dangerous currents, especially in winter on north and west-facing shores.