The Sustainable Development Goals Working Group (SDGWG) of the International Council on Monuments and Sites (ICOMOS) advocates for heritage by publishing reports, attending conferences and engaging in networking. The SDGWG is particularly interested in how water, heritage and sustainable development intersect. Various aspects of this intersection are demonstrated by three case studies of underwater cultural heritage: a study of submarine cables and pipelines, the traditional floating garden system of chinampas in Mexico City, and the indigenous water tanks of kulams and gender-associated stepwells in India. This paper examines the current state of protection and advocacy, while also discussing the challenges faced by water heritage. While significant challenges remain, the SDGWG is developing solutions to ongoing and sometimes overlooked problems.