Seashore's features include:
- Full support for the GIMP's native XCF file format
- Read and write support for the TIFF, PNG, JPEG and JP2000 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
- Support for over 50 effects with CoreImage
- Tablet support
- ColorSync support (including embedded profiles in TIFFs and CMYK previewing)
Most features work on Mac OS 10.3.9 and later, with the exception of JP2000 support for which Mac OS 10.4 is required and CoreImage effects for which Mac OS 10.4 and a G4, G5 or Intel processor is required.