You’ve scoured through the waters for a while and notice your buddies signal thumbs-up, it’s time to ascend. Quickly recounting your dive training sessions, you look around the surface for boats, double check your computer and slowly elevate.
Sounds pretty straightforward- but there’s a lot more that goes into it.
As a newbie or even an intermediate diver, the ascension process can be daunting. Your nerves are still adjusting to this novel experience, you’re more vulnerable and likely to panic underwater. In fact, inexperience and anxiety are two of the top three reasons divers rush to the surface too quickly- which can cause serious decompression sickness and injuries.
It goes without saying that you should remember the standard ascent procedures that will bring you back to positive buoyancy by heart, both in theory and practice. There’s a decent amount of information to retain about this crucial part of your dive and it’s all fun and games until you can’t recall it when it matters most.
It’s a known best practice to carry a reliable Dive computer that shows you nitrogen levels, ascension rate, direction and altitude on a handy screen not more than 8 ounces heavy. One glance and you’re caught up with every important detail and have a clear idea of what to do next.
Though once you learn the ropes getting to the surface won’t concern you one bit- every pro diver started somewhere.
We put together this concise guide that will walk you through each aspect of a safe ascent, sourced from professional insights and the widely trusted PADI system.
What happens when you ascend?
To put it simply, you go through nitrogen off-gassing.
When you’re swimming at a certain depth, the water pressure causes more nitrogen to absorb in your tissues. The deeper you go, the higher nitrogen levels in your tissues get.
As you elevate upward though, water pressure around you decreases and nitrogen is released into your bloodstream, which your circulatory system finally carries to your lungs. This gas leaves your system completely when you reach the surface.
Here’s the catch- how fast you ascend determines if that nitrogen successfully gets to your lungs or gets stuck in your bloodstream as bubbles. These bubbles stuck in your system cause decompression sickness. Fatigue, numbness, chest pain and aching muscles and joints are just a few effects of this at-times fatal illness.
Besides this, if you accidentally over-pressurize the airspace by performing something like a Valsalva, it can cause ear barotrauma. There’s also the risk of bumping your head into a boat you didn’t see coming.
Risky stuff, but completely avoidable when you make it a point to follow the rules of safe ascent.
How to safely ascend?
What qualifies as a safe ascend has long been a point of debate in the diving community. Back in the 90s, consensus dictated that 18 meters/ 60 feet per minute was a safe ascension rate for divers of all levels. After a dozen cases of DCS from swimming up too quickly, the agreed rate has since dropped to 9 meters/ 30 feet.
Though there are some widely accepted steps that aren’t questioned often- if at all. Most pro divers and trainers swear by them. Before we talk about them in a little more detail, let’s get something crucial out of the way- deflating your buoyancy control device (BCD).
If you’ve been diving for a while, the feeling of “getting light” underwater might be way too familiar. Ringing some bells? Most divers have had times when they felt themselves drifting above, let out some air from their BCD, maintained buoyancy and moved on.
Venting gas out of your BCD neutralizes the buoyancy and sets the stage for the whole ascent. Your BC’s filling up with air, dumping all of it out before starting to ascend is a best-practice every diver follows. Although super experienced divers know how to maintain neutral buoyancy just by breathing the right way- that’s way too risky an option for new and intermediate divers.
Know your BCD and the way its exhaust valves work- where is the hose located and is it accessible enough?
The PADI Open Water Course asks you to keep the Acronym S.T.A.R.S in mind when moving upward.
The dive plan you drew up with your buddies might have included time for ascension. You start out by letting your them know that you’re ready to ascend using the thumb up hand gesture and get their confirmation in return.
Timing the whole process is essential for safety. Keep an eye on your dive computer to mentally register your remaining air and decompression limit. It’s best to start ascending a little early to make sure fatigue or cold don’t set in. If your no-decompression limit goes overboard, make up for it by stopping at certain points and informing your buddies with the signal.
Even if you don’t feel the need for it, it’s a good practice to stop midway for 3 minutes for dives deeper than 10 meters / 33 feet- probably around 15 meters below the surface.
Check if there’s any obstacle between you and the surface. Do you see any vessels or kayaks headed right towards the spot where you’ll emerge? Keep your eyes and ears vigilant for any sign of a boat on the surface- you’ll hear the propellers before you see the boat coming.
Though it’s common for divemasters to have a dive-flag buoy in boat-crowded areas that fill in your location to any nearing watercraft. Try to surface close to the dive buoy and you’ll do just fine.
When you’ve crossed the 15-meter stopping point, switch to neutral buoyancy until you’ve surfaced. Here’s when you’re taking the foot off your vehicle’s pedal on a rocky mountain road- you go as slow as possible. Rotate to know what’s around you and keep track of any obstacles. Extend your arms above your head to announce the surfacing to other divers and boats on the surface.
There’s a slight you would encounter last-minute obstacles on the surface- or just boat traffic making surfacing a pain. In these situations, it’s best to switch direction and swim elsewhere below the surface or wait until the surface clears out.
Once you rotate to make sure there’s nothing in the way, swim towards the surface at a slow pace without using your BC. Inflate it once you’re on the surface to keep you afloat and positively buoyant up there. Keep your regular in your mouth until you’ve inflated the BC to check the surface conditions one final time.
Viola! You’ve emerged successfully from a great dive.
Don’t rush yourself once you’re up on the boat ladder or the shore. Give yourself time to rest, consider extending your surface interval after particularly deep and long dives. Hydrate and relax.