Isoprene is a climatically important biogenic volatile organic compound with oxidation in the atmosphere leading to ozone and aerosol production. While predominantly terrestrial, isoprene can be sourced from the ocean, although this needs to be quantified. This thesis quantified isoprene emissions from coastal benthic systems where isoprene was expected to be concentrated using an improved method. Coastal marine habitats were identified as both a source (carbonate sediments, seagrass) and sink (mangrove, seagrasses) for isoprene, with species-specific patterns being observed in seagrass communities.