How to Ascend from a Dive

A recent accident in Koh Phi Phi’s Maya Bay, Thailand, wherein two surfacing Russian scuba divers were struck by a speedboat propeller, resulted in one of them losing a leg and the other receiving deep lacerations. When accidents like this occur, it’s worth revisiting the safest possible ascension procedures. The exact details of the accident are still unclear, so this article is in no way intended to assign blame or claim to know how it could have been prevented. Rather the incident serves as a reminder that, as scuba divers, we must always be vigilant as we ascend in mid-water to minimize the risk of run-ins with passing watercraft. Here are a few of our tips on how to ascend from a dive.

Carry a Dive-Flag Buoy

If you’re on a guided dive in an area with boat traffic, the divemaster should have a dive-flag buoy, which will accompany your party on the surface during the entire dive to let watercraft know exactly where you are underwater. When it’s time to surface, do so as near as you can to the buoy. If it’s just you and a buddy on a dive, one of you should deploy the dive-flag buoy for the same reasons. 

Start Early

Once it’s time to ascend, remember that a proper ascent takes some time, so make sure to begin by taking into account your remaining air, your no-decompression limit and personal factors, such as cold and fatigue. Ascend while you’re still fresh and on top of things. 

Go Slow

Most organizations recommend a maximum ascent speed of 30 feet (9 m) per minute. Orient yourself as you begin your ascent, getting an idea of where you are in terms of your planned surfacing point. Start looking up to get an idea of the conditions above. Is the sea calm or choppy? Do you see a lot of boat traffic, or do you have the water to yourself? As you ascend, also keep an eye on your depth gauge and timer to make sure you’re rising slowly enough. 


Even if it isn’t a requirement for non-decompression dives, pretty much all dive organizations and dive computers recommend a safety stop for any dive deeper than 33 feet (10 m), typically at 15 feet (5 m) for three minutes. Use the time during your safety stop to scan the surface for any boats (including your own dive boat), kayaks, or other vessels you may need to navigate around. Listen for propellers as well, as you’ll hear a boat much sooner than you’ll be able to see it. You won’t be able to determine where it’s coming from though, so watch the surface for it.


When you’ve finished your safety stop, become neutrally buoyant before beginning your ascent, and maintain neutral buoyancy throughout. Fin very gently if you must to ascend. Keep the ascent rate as slow as possible, but don’t spend the entire time looking at your dive computer. Instead, look around, scanning the surface. Rotate as you ascend to give yourself a 360-degree field of vision. Most organizations recommend that you ascend with one hand above your head, holding your low-pressure inflator at the highest possible point to allow you to quickly release air from your BCD if your ascent becomes too fast. This is also partly to ensure that if you do have an unfortunate encounter with a boat propeller, at least it will be your hand and arm that takes the hit instead of your head. If there’s boat traffic overhead, you may want to delay your final ascent until it’s clear, air-permitting, or swim to another location. 

Come up Close

Ascend as close to your dive boat or dive buoy as you can, as mentioned above, since other boats will typically keep their distance. If you have neither, and there is boat traffic in the area, send up a DSMB before surfacing to give boats and other vessels fair warning that people are coming up.

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