Seashore's features include:
- Full support for the GIMP's native XCF file format
- Read and write support for the TIFF, PNG, JPEG, JP2000 and GIF file formats
- Read-only support for the BMP, PICT, PDF and XBM file formats
- Layers with over 20 merging effects
- Ability to edit just the primary or alpha channels
- Thorough transparency effects including semi-transparent gradients
- Arbitrary selection regions
- Anti-aliased brush strokes
- 6 basic gradient effects with 16 variations
- Tablet support
- ColorSync support (including embedded profiles in TIFFs and CMYK previewing)
- Plug-in filters
Most features work on Mac OS 10.3 and later, with the exception of JP2000 support for which Mac OS 10.4 is required.