List of SSSIs in West Gwynedd

West Gwynedd AOS
Lists of Sites of Special Scientific Interest in West Gwynedd (1974–1996) comprise:
- List of Sites of Special Scientific Interest in Anglesey
- List of Sites of Special Scientific Interest in Gwynedd

Lists of Sites of Special Scientific Interest in West Gwynedd (1974–1996) comprise:
| National parks |
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| National Landscapes (AONBs) |
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| Heritage coasts | ||||
| Nature reserves | ||||
| Site of Special Scientific Interest | ||||
| EU designations | ||||
| Other designations | ||||
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