This unique nautical chart is made from Baltic Birch wood, which is carved to create a three-dimensional chart. The "Bathymetric Chart" is labeled with ocean depths, shoal names, areas of Nantucket, and more. The chart is created with the help of a professional cartographer to assure accuracy. Check the photos to see the level of detail for various depths. Each chart is framed in dark, solid wood. Measures 16" x 20".