Captain James Cook’s voyages were responsible for extensive data collection on geography, geology, biota, currents, tides, and water temperatures of the Atlantic and Pacific oceans in the 1760s and 1770s. In 1820, Alexander Marcet noted the varying chemical composition of seawater in the different oceans. Not long after, in 1843, Edward Forbes, a British naturalist, stated that marine organisms could not exist deeper than 300 fathoms (even though many had already collected organisms much deeper, many followed Forbes' influence).