Master Your Trim: The Skill That Fixes Everything Else

Every October, as our divers start layering up for dry suit season, we see the same thing happen on the first few dives of the autumn. Perfectly competent divers suddenly finning like they are riding a bicycle uphill, knees dropped, fins clawing at the water, clearly working far harder than they need to. Almost every time, the cause is the same. Trim has quietly gone wrong, and nobody has noticed because it happened gradually as kit changed with the season.

Why Trim Matters More Than Most Divers Realise

Trim is your body's orientation in the water, ideally close to horizontal with your fins slightly below the rest of you, rather than the classic beginner posture of head up and feet dangling. Good trim matters because it directly affects how much effort you spend fighting the water rather than moving through it. A diver in poor trim burns air faster, kicks up silt they then have to swim through, and puts unnecessary strain on their body across a long dive. It is one of those foundational skills that quietly improves almost everything else once it clicks.

Common Trim Mistakes We See

The single most common mistake is weighting for the average dive rather than for correct trim specifically, which usually means divers are carrying too much weight around their waist and not enough distributed to counter it. This drags the hips and legs down, forcing a head-up, feet-down posture that no amount of finning technique can fully fix. The second common mistake is treating trim as fixed rather than something that needs rechecking every time your kit configuration changes, which is exactly why the start of dry suit season catches so many divers out. A dry suit, thicker undersuit, and different weighting all shift your centre of buoyancy, and last season's trim setup often simply does not apply anymore.

The Dry Suit Season Trap Specifically

Air trapped in a dry suit tends to migrate toward whichever part of your body is highest, and if that is your legs, you will find your feet drifting upward uncontrollably no matter how well trimmed you were in a wetsuit. Getting comfortable venting a dry suit correctly, and rebalancing weight to account for the suit and undersuit, is essential groundwork before your first proper dry suit dive of the season.

How to Actually Practise Trim

The best place to start is a controlled pool or shallow, calm water session where getting it wrong costs you nothing except a slightly awkward few minutes. Hover in mid-water with no fin movement at all and notice which way your body naturally tips. If your legs sink, you likely need weight moved higher, toward your tank band or trim pockets, rather than simply added or removed. If your head drops, the opposite applies. Small, incremental changes matter far more than big ones, and a genuinely well-trimmed diver often only needs a kilogram or two moved from one position to another rather than a dramatic overhaul.

Using Video to See What You Cannot Feel

Trim is notoriously hard to self-assess from the inside, because a few degrees of tilt can feel level when you are the one experiencing it. If you can get a buddy or instructor to film a few minutes of you hovering and finning, it is often genuinely eye opening. Most divers are surprised by how far off level they actually are compared to how it felt underwater.

What Instructors Actually Look For

When we are assessing trim on a course, we are watching for a stable horizontal position that holds even when a diver is distracted, checking a gauge, deploying a surface marker buoy, or dealing with a simulated problem. Trim that only holds when a diver is concentrating on nothing else is not yet reliable trim. We also look at fin position, since dropped knees and a bicycle-style kick almost always trace back to weighting or body position rather than a finning technique problem in isolation. Fixing the underlying trim issue is usually far more effective than endless drilling on kick style alone.

Trim and Buoyancy Work Together

It is worth being clear that trim and buoyancy are related but different skills. Buoyancy is about how much you weigh overall in the water, while trim is about how that weight is distributed across your body. You can be perfectly neutrally buoyant and still have terrible trim if all your weight sits in the wrong place. Genuinely comfortable, low-effort diving needs both dialled in together, which is exactly why we treat them as a combined focus area rather than teaching them in isolation.

Where to Go From Here

If your trim has never quite felt right, or if you know it changes every time you switch between wetsuit and dry suit, a dedicated peak performance buoyancy style session is genuinely one of the best investments you can make in your diving. It is not a flashy specialty, but divers who put the work in almost always report it as the single course that made the biggest practical difference to how much they enjoy being underwater. Browse our full course listings to find a session that fits, or speak to an instructor about building trim work into your next dry suit dive.

Trim Drills to Build Muscle Memory

Beyond the basic mid-water hover, a few specific drills genuinely accelerate progress. Fin pivots, where you use only your breathing to lift and lower your body off the bottom while remaining horizontal, build a strong feel for how buoyancy and body position interact. Practising a slow, controlled somersault in open water, once you are confident with buoyancy, is another good test of whether your trim holds up when your orientation changes completely rather than staying fixed in one position. Even something as simple as retrieving an object from the bottom without your knees or fins touching down forces genuinely good trim, since any sloppiness in body position becomes immediately obvious.

How Trim Changes Across Different Dive Types

Trim is not a single fixed setting you dial in once and forget. Photographers often need slightly different trim to hover steadily while framing a shot with a camera housing changing their centre of gravity. Divers using a single large torch for UK low-visibility diving need to account for the extra weight held out in front of them. And as covered above, dry suit divers need to rebalance entirely compared to their wetsuit setup. Recognising that trim is configuration-specific, rather than something you learn once and apply everywhere unchanged, is itself part of becoming a genuinely skilled diver.

A Few Things to Try on Your Next Dive

Before your next dive, do a proper mid-water hover check before you even start swimming, rather than assuming last season's weighting still applies. Pay attention to where your fins sit relative to the rest of your body throughout the dive, not just at the start when you are fresh and paying close attention. And if something feels like harder work than it should, resist the urge to blame fitness or fin choice first. More often than not, trim is the real answer.

Want hands-on help dialling in your trim before dry suit season gets fully underway? Explore our courses or get in touch to book a session, we're at Bellman Court, Great Knollys Street, Reading, or call +44 (0) 118 9761 729.