Ulva laetevirens (Areshoug 1854) is a green alga, which grows in sheets or blades, and is one of a group of species commonly called 'sea lettuce'. Ulva laetevirens was described from Port Phillip, Australia, and is found in Australia and New Zealand, presumed to be its native region. It has been introduced to the Mediterranean Sea, Sweden, and New Brunswick. In US waters, it was collected in US waters in 2011, in Long Island Sound, and in 2013 in Jamaica Bay. Sea lettuce' is routinely casually identified as 'Ulva lactuca Linnaeus 1758', so its species diversity is often overlooked, this alga requires genetic identification so that the extent of its range is poorly known. Likely vectors are hull fouling and ballast water. Ulva laetevirens s one component of algal blooms identified as 'green' tides in Jamaica Bay, although the blooms were dominated by the native U. compressa in Jamaica Bay.