Seagrass meadows across northern Australia support dugongs, green turtles, and coastal fisheries of deep cultural, conservation and economic significance. These ecosystems face increasing pressures, yet detecting and responding to change requires monitoring that is consistent, repeated, and spatially appropriate — capacity that in remote northern Australia lives with Indigenous Ranger programs. Rangers’ knowledge of culturally significant areas, sites of concern, and observed environmental change is irreplaceable for co-designing monitoring that is relevant, targeted, and grounded in long-term relationships with Sea Country — shaping where monitoring happens, what questions are asked, and how change is understood. Emerging technologies are transforming what is possible in marine monitoring, and Rangers are at the forefront of deploying them. Method choice must still be matched to habitat, resources, and the management question, whether pinpointing localised impacts or tracking large-scale resource condition for megafauna. To support Ranger groups, we are co-developing a decision-support toolkit, including publicly available operating procedures, species guides, and training videos, that puts the right method in the right hands. Workshops build Ranger skills in emerging technologies and image analysis, while accessible data platforms ensure that data is managed with community control and contributes to a growing picture of seagrass condition across northern Australia.