Spending an excessive amount of time in the bathroom/loo/privy, especially when others need to use it. Scuba Diving can interfere with other peoples' busy schedules, as there is much time wasted. Whilst sometimes a person may spend a long time on the toilet due to legitimate natural reasons, roughly 80-90% of Scuba Diving is caused by reading newspapers, making phone calls, or playing around with electronics devices. Scuba Diving can be done by both men and women, but under different circumstances: for instance, women naturally spend absurd amounts of time in the bathroom usually messing around in the mirror as is, whilst men can spend about 30 minutes on the can playing Angry Birds or something.

The term comes from the idea that the reason why the person is in the bathroom so long is because they're literally swimming around in the toilet water rather than doing their intended business.
Ted: For Christ's sake, man, Billy's been in there for like 45 minutes! I have to take a piss really bad!
George: I know, me too -- what the hell is he doing, Scuba Diving in there!?

Roger: Damn it, I got to shit really bad, but there's only one available stall in our building's men's room, and some damn old guy's been in there for ages with his newspaper. God damn it, I hate Scuba Diving!

Jason: Dude, we've been waiting for a fucking long time to go and pick up our pizza. What the hell were you doing in there, Scuba Diving?
Tom: Nah brah, I got the Farmville app!
by Bo Andysin February 10, 2014
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When a guy pees with his dick submerged in the toilet
Al has an ankle slipper so he goes scuba diving every time he pees
by Big38HawkEm January 1, 2021
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When you lay on your back and suck your own dick while your balls sag onto your eyeballs.
I tried scuba diving last night. Totally felt like I had a snorkel in my mouth and goggles over my eyes
by CrystalPepsi March 12, 2015
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the act of pretending to give a high five then sweeping ur hand under theirs saying scuba dive while smacking them in face with ur other hand
scuba diver : hey nice job

other dude : thanks
scuba diver : high five

other dude : Yeah !!!!

scuba diver SCUBA DIVE BITCH!!!!
SMACK
other dude : oww
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When a guy slides a hand down his pants without realizing it. Normally happens while watching T.V.
Hey bro my girlfriend is coming over, will you make sure your not scuba diving in front of her like you always do.
by teitezzy January 3, 2011
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When you eat a girl out while taking a bath together
Dude, Tracy and I went scuba diving together last night.
by SuckMyDillon October 9, 2017
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