Human interest in the sea fuels a multi-billion dollar a year ocean tourism industry. Ocean tourism refers to pleasure travel in which the sea is the primary focus of activities. Ocean tourism comes in many forms including cruises, ecotourism, and fishing expeditions.

Cruising the Oceans

Cruises are one of the most popular forms of ocean tourism. In the late nineteenth and early twentieth century, cruise liners were needed to carry passengers across the oceans. Many of these cruise ships—including the ill-fated Titanic, which sank in 1912 killing over 1,500 people—provided passengers a luxurious way to travel. Originally powered by steam-driven engines, most modern cruise ships use diesel fuel to power their engines.

Sailboats moor off the Tahitian islands, a popular tourist destination in the South Pacific. © Neil Rabinowitz/Corbis. Reproduced by permission.

While cruise ships were needed for Atlantic Ocean crossings, by...