On La Vagabonde what Citizen Science is Possible?
Ok, trying an answer. I don't know if citizen science is actually done. Possible would be sample collection, physical data (water temperature, air temperature), weather conditions, sigthings of rubbish, animals or unusual phenomena. Actually, before the space age ships collected and exchanged weather data to produce on ship weather charts for example. Afaik, this is not practical any more, merchant ships anyway and increasingly recreational vessels (if the owner can afford) have satellite data and internet on board.

Data collection in itself is no problem, but the calibration to make them comparable and combinable is. In simple words, one can't just buy a thermometre and bind it to the mast, they'd differ by a lot. Recreative vessels have their routes on the oceans. In Atlantic terms, now (November) they set out in hundreds and thousands into the Caribbean, in spring some them return (the northern route is more strenuous ;-)). There is not that much to be had science wise because they all measure similar things (in between the sunbathing on their catamarans).

And, there actually is concern that too much citizen science could leave a negative carbon footprint.

Something to read: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4159111/