It's happened! It's finally happened!! After over 30 years since its first mention in televised Star Trek (TNG's "Yesterday's Enterprise" in 1990), cetacean ops (operations) has made it on screen in Lower Decks' final episode of season two, "First First Contact"!
Cetacean ops is an area aboard Federation starships (and spacestations as well as planet-based facilities, I shouldn't wonder) for crew who prefer a certain moistness, i.e. being submerged. In the Star Trek universe, whales and dolphins are sapient (as I'm sure they are in our universe, but getting the majority of humans to recognise that is a topic for another place & time) and seem to enjoy the same privileges as other sapient beings, including joining Starfleet and serving on a starship.
In Lower Decks (LDS), as with the Star Trek The Next Generation Technical Manual, and the USS Enterprise NCC-1701-D Blueprints, the cetaceans (beluga whales in LDS, and dolphins & Takaya's whales (a type of Orca] in the TNG tech manual and blueprints) are navigation specialists.
Here are some screenshots I took of USS Cerritos' cetacean ops from "First First Contact" (owner/creator ViacomCBS) - minor spoilers ahead for the episode:
Just like with certain other cetaceans, Kimulo and Matt are all for some fun sex play, and Rutherford is a particular favourite of theirs it would appear (and who can blame them!):
As we didn't get to see it in the episode (due to heroics and timing), here's my interpretation of how the fun times could have started: