Santa Catalina Island is part of the beautiful Channel Islands Archipelago, which stretches for miles along the Southern California coast. 22 miles long and 8 miles wide at the widest point, the island is both rugged and beautiful, and has some of the richest marine diversity in the world. Catalina Island is the only Channel Island that is developed, but most of the island is still protected, and most the inhabitants are concentrated in the town of Avalon.