Management decisions for the conservation of the Great Barrier Reef require efficient access to an ocean of data. A fit-for-purpose, cloud-based Data Management System (DMS) offers a one-stop shop for over 150 datasets, providing over 3,000 variables on human impact and human perceptions, coral health, water quality, biodiversity, oceanography, satellite-derived products, model data and more. This system leverages the efficient Analysis-Ready Cloud-Optimised ARCO data formats that enable faster data analysis: (1) ARCO extractions can be up to 5 times faster than working with local files, accelerating research and decision-making; (2) access and analyse massive datasets (over 10TB) directly in the cloud, eliminating the need to download entire collections or individual files. The DMS is also equipped with a robust data and metadata API, allowing the creation of workflows that could be used to produce self-updating dashboards and reports. Automatic updates of the data, publicly available comprehensive tutorials, and customisable Python/R notebooks empower researchers and managers to transform GBR-related data into actionable insights, paving the way for sustainable reef management.