Environmental sciences depend heavily on observational data. Successful studies of ecological processes in lakes require in-situ data that cover the relevant temporal scales from milliseconds to entire seasons. Temporal and spatial coverage requirements represent a non-trivial challenge in lake sciences, which have traditionally used sampling campaigns conducted from research vessels or anchored moorings. These come with various logistical tasks and impose constraints on data coverage. An open water platform can overcome many of these limitations by providing continuous access and a wide range of analytical capabilities in direct contact with the lake environment. A consortium of five partner institutions constructed a 10 × 10 m, open-water, multipurpose platform on Lake Geneva (Switzerland/France) for a broad range of limnological research. The LéXPLORE platform, anchored since February 2019 at a position reaching 110 m depth off the lake's north-shore, provides workspace for a large number of instruments and up to 16 staff working in parallel on individual or integrated multidisciplinary projects. The safe, dry and protected floating laboratory offers direct access to the lake environment for high-sensitivity, high-throughput analyses including those which might advance sensor technology. The platform provides flexible workspace for both high-resolution measurements and investigations of larger-scale external forcing. It thus supports multidisciplinary empirical research in limnology, atmospheric sciences, and remote sensing. This article describes the platform and how it will advance aquatic sciences. The large number of projects that have already requested access to the platform demonstrate the efficacy and necessity of the LéXPLORE concept.