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Shallow nearshore coastal waters provide a wealth of societal, economic, and ecosystem services, yet their topographic structure is poorly mapped due to a reliance upon expensive and time intensive methods. Space‐borne bathymetric mapping has helped address these issues, but has remained largely dependent upon in situ measurements. Here we fuse ICESat‐2 lidar data with Sentinel‐2 optical imagery, within the Google Earth Engine cloud platform, to create openly available spatially continuous high‐resolution bathymetric maps at regional‐to‐national scales in Florida, Crete and Bermuda. ICESat‐2 bathymetric classified photons are used to train three Satellite Derived Bathymetry (SDB) methods, including Lyzenga, Stumpf, and Support Vector Regression algorithms. For each study site the Lyzenga algorithm yielded the lowest RMSE (approx. 10%–15%) when compared with validation data. We demonstrate a means of using ICESat‐2 for both model calibration and validation, thus cementing a pathway for fully space‐borne estimates of nearshore bathymetry in shallow, clear water environments. Plain Language Summary: Knowledge of the depth of the shallow seafloor in coastal waters is needed for a wide range of applications, including navigation and habitat monitoring. Mapping water depth in these locations is expensive, arduous and sometimes dangerous. To overcome some of these challenges, we used multiple satellite data sets to map water depth in several unique coastal environments. ICESat‐2 lidar data is able to sample the depth of the seabed along straight lines in clear water and is then combined with other satellite imagery to derive water depth maps, with acceptable error, containing a level of detail that can exceed some field collected measurements. Key Points: Nearshore bathymetric depths can be retrieved using ICESat‐2 lidar dataICESat‐2 bathymetric data can train Sentinel‐2 Satellite Derived Bathymetry (SDB) models at shoreline to island nation scalesThe fusion of ICESat‐2 and Sentinel‐2 data paves the way for openly available nearshore bathymetry mapping from space [ABSTRACT FROM AUTHOR]