in which specific areas are they commonly found?
Generally in tropical waters between the latitudes of 40°N and 37°S. The places include  North Carolina to Uruguay,  Morocco to Senegal, the Mediterranean Sea, along the rim of the Indian Ocean , and in the Pacific Ocean.
Great hammerhead
The great hammerhead inhabits tropical waters around the world, between the latitudes of 40°N and 37°S. In the Atlantic Ocean, it is found from North Carolina to Uruguay, including the Gulf of Mexico and the Caribbean Sea, and from Morocco to Senegal, and the Mediterranean Sea. It is found all along the rim of the Indian Ocean, and in the Pacific Ocean from the Ryukyu Islands to Australia, New Caledonia, and French Polynesia, and from southern Baja California to Peru. 
what is 'great hammerhead'? The largest species of hammerhead shark. what is the length of these largest species? UNANSWERABLE
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Great hammerhead [SEP] Distribution and habitat
The great hammerhead inhabits tropical waters around the world, between the latitudes of 40°N and 37°S. In the Atlantic Ocean, it is found from North Carolina to Uruguay, including the Gulf of Mexico and the Caribbean Sea, and from Morocco to Senegal, and the Mediterranean Sea. It is found all along the rim of the Indian Ocean, and in the Pacific Ocean from the Ryukyu Islands to Australia, New Caledonia, and French Polynesia, and from southern Baja California to Peru. It may occur off Gambia, Guinea, Mauritania, Sierra Leone, and Western Sahara, but this has not been confirmed. Great hammerheads may be found from inshore waters of less than deep, to a depth of offshore.