Ecotourism presents an opportunity to provide equitable benefits to local communities; serve as a platform for environmental education; and can be leveraged to support conservation initiatives, shifting away from traditional mass tourism and other forms of unsustainable marine use. Marine ecotourism sectors, such as scuba diving, whale and shark watching are increasingly important for local economies but their aggregate benefits are often overlooked in global ocean economy discussions. Here, we present a first estimation of the global economic value of scuba diving, including 11,500 identified scuba dive operators across the world. Based on an online operator survey, we estimate global annual revenue (direct diving expenditure in 2019) at between 0.9–3.2 billion USD per year, and the broader economic impact (direct and indirect expenditure) at between 8.5 and 20.4 billion USD per year. Marine tourism is one of the largest sectors in the ocean economy, and with 8.9–13.6 million marine diving tourists worldwide supporting up to 124,000 jobs, the scuba diving sector could be at the forefront of transformative change for local and global ocean equity and sustainability.