 The range of underwater vision is usually limited by turbidity.In very clear water visibility may extend as far as about 80m, and a record Secchi depth of 79 m has been reported from a coastal polynya of the Eastern Weddell Sea, Antarctica.In other sea waters, Secchi depths in the 50 to 70 m range have occasionally been recorded, including a 1985 record of 53 m in the Eastern and up to 62 m in the tropical Pacific Ocean.