A free vehicle benthic lander designed to characterize reaction at and transport across the sediment–water interface. ROLAI2 was designed for long duration deployments (i.e. greater than 30 days) to measure the small fluxes and low reaction rates typical of most of the deep ocean. The lander does this my autonomously collecting sediment and pore water samples as well as samples from benthic chambers. Tracers can be released into the chambers to define such processes as non–diffusive exchange across the interface.