Diving sites are included in Open Street Map data with the sport=scuba_diving tag, at time of writing there are currently 3,842 entries with this tag across the world. Including many in Cyprus. There are multiple ways of viewing and using Open Street Map data, Open Sea Map is one of them (if you enable the "sport" layer under the view dropdown. Another option is to use an Overpass query like this one, move the map to anywhere in the world and click the "run" button to see them highlighted.
Open Street Map is completely collaborative, anyone can add data to the dataset. Although be aware that some users may not update their copy of the data regularly so it may take some time for any additions to appear (Although Overpass should take seconds). So please do add any that you know to be missing, if you have not contributed to Open Street Map before I'd highly encourage you to read through the beginners guide first and then the documentation for the sport=scuba_diving tag. I'll particularly highlight though the importance of not just copying data from any other sources into Open Street Map, the exact copying and licencing requirements are beyond the scope of this answer but more information is available on the Open Street Map Wiki. Also any data you add should be verifiable, meaning that there should be enough physical presence that anyone (including a non-diver) who visits the site should agree that this is a diving site, see this wiki page for more information.
If have got some contributions to make then the easiest way to add them is to go to: https://www.openstreetmap.org/ then:
- Click edit and follow the instructions to create an account
- Click point at the top and then the location you want to add the point on the map
- Enter "point" as the search term and click it
- Scroll down the left panel to the tag section, enter "sport" in the left and box and "scuba_diving" in the right hand box.
- Add any other information (name ect.) to the point
- Click on Save
- Add a comment explaining your changes (eg. adding diving spots)
- Add a source for the information, this is optional but recommended. Something like "local knowledge" is absolutely fine is that's true. "Survey" can be used if the information is based on you having been to the site.
- Click upload