Working on & off on a scuba diving site which allows you to log dives, sites, photos & sealife.
Currently only South Australian & Victorian dive sites, but probably the most extensive collection of either.
Live website here: https://divedb.net/
Source here: https://github.com/cetra3/divedb
Currently exploring activitypub integration, being able to log dives and have people follow/comment/react to them from the fediverse