Super Mario 64 Swimming Guide: Tap A, Don't Hold It

Holding A is the slow way to swim in Super Mario 64. Hold it and Mario switches to a flutter kick that settles at 12 units per frame. Tap it in the right rhythm and his breaststroke climbs to 28, the ceiling the game's code puts on swimming speed. Same button, more than twice the speed.

The breaststroke has a real-world origin. The Guardian's 2020 feature on Mario's 35th anniversary notes that Shigeru Miyamoto took up swimming, and got very keen on it, while Super Mario 64 was in development, and points to Mario's breaststroke as the result. The code behind that stroke is fussier than the animation suggests, and the n64decomp decompilation of the game spells it out. Everything here comes from that decompilation unless a sentence says otherwise, with Ukikipedia and the Super Mario Wiki filling in the rest.

Speeds are in the game's own units per frame. Super Mario 64 runs at 30 frames per second, per Ukikipedia, so 28 units per frame is 840 units per second. This covers the N64 game, which Super Mario 3D All-Stars and the Nintendo Switch Online app both run a version of; the DS remake's differences are near the end.

Every swimming input in one table

Two of those rows are worth a sentence each before the speed numbers.

B is a grab, not a punch. In the decompiled interaction code, a hit on an enemy has to come from a move flagged as an attack, such as a punch, a kick, a ground pound, a slide kick or a shell ride, or from jumping onto or into something in mid-air. No swimming action qualifies, so Mario has no way to hit an enemy while he swims. Everything in the water is something to steer around, and the health guide has what each one costs you.

The stick works like a plane's. Forward points Mario down, so pushing forward to swim ahead takes him toward the floor. Pull back to level out.

Why holding A is the slow way

Tap A and Mario does a breaststroke: a 13-frame stroke that adds speed in two bursts, then a glide that bleeds a quarter of a unit every frame. Keep A held through the end of a stroke and the game turns it into a flutter kick, which eases his speed toward 12 and keeps it there.

The difference between slow and fast swimming is a hidden number Ukikipedia calls swimming strength. It starts at 160 and tops out at 280, and the code divides it by 10 to get the speed above which Mario loses an extra half unit every frame. At 160, that drag starts above 16. At 280 it starts above 28, which is the cap anyway, so it stops applying.

Run the code's speed rules frame by frame, in a straight line with no current, and the input habits sort themselves out:

Those averages are our own model of the decompiled code, not a figure from either wiki. They match Ukikipedia's description of strength rising from 160 to 280 and raising Mario's top speed as it goes.

The stroke rhythm, step by step

Strength only goes up at two moments, both in the decompiled stroke code:

1. Let go of A before the stroke finishes. When a stroke ends with A up, the game adds 10 as Mario rolls into his glide.
2. Have A down seven frames into the glide. The game adds 10 more and starts the next stroke on that frame.

It drops straight back to 160 if you hold A through the end of a stroke (that is the flutter kick), press A again early in a stroke (on its second to fifth frames, which queues a restart and resets the count), or do not have A down by the time the glide is seven frames old. A stroke started from a standstill also begins at 160.

So the method is: press A, let go while Mario is still stroking, then press and hold A again as soon as the stroke ends. You do not have to hit that frame yourself. If A is already down, the game starts the next stroke right on it, so pressing early in the glide is free and pressing late resets you. One stroke plus that glide is 20 frames, which makes the beat three strokes every two seconds, and six well-timed strokes take strength from 160 to the 280 ceiling.

There is an audio cue for it. At the start of each stroke, the decompiled code checks strength and plays a different stroke sound effect whenever it is above 160, which only happens when the stroke before it was chained correctly. When the sound changes, the rhythm is landing.

Steering: the stick flies Mario like a plane

Push forward and Mario points down; pull back and he points up. The further you push, the steeper he goes, up to just short of vertical. The code adds two details worth knowing:

• He tilts twice as fast while level or pointing up as while pointing down. His angle changes by 512 angle units a frame (out of 65,536 in a full circle) while he is level or pointing up, and by 256 while he is pointing down. From level, pointing straight up takes about a second and pointing straight down about two.
• Turning builds up. Turn speed rises by 16 angle units a frame to a top of 640, about 3.5 degrees a frame. From a straight swim, a full U-turn takes roughly 2.4 seconds, so line up long swims before you start them.

Swim into the sea floor and the code levels Mario out along it; swim into a ceiling and it tips him down. The camera changes with depth as well: within 400 units of the surface the game uses its water-surface camera, and deeper than 800 it moves to one behind Mario. The camera guide notes that those two keep their own cameras even with Mario cam on.

Getting in: what a dive keeps

Mario only starts swimming once he is more than 100 units below the surface. Shallower water is for wading: he walks through it like ground.

When he falls into deeper water, the entry code:

• keeps a quarter of his forward speed and half his falling speed,
• places him 100 units under the surface, however far he fell,
• and runs no fall-damage check at all, which is why the movement guide lists landing in water as a way to cancel fall damage.

Arrive in a dive (B in the air with more than 28 units a frame of forward speed; any slower and B is a jump kick) and Mario keeps pointing downward as he goes in. Hold A as you hit the water and a flutter kick starts as soon as the splash ends.

Getting out: the water jump and the shoreline

Mario has two ways to get himself out of deep water, plus a third for Metal Mario further down.

Swim to a shore. When Mario reaches the surface over ground that rises to the waterline, the code stands him up and he walks out.

The water jump. At the surface, with Mario level or pointing up, pull the stick almost all the way back and press A. The code wants the stick past 60 on a scale that tops out at 64, so a half-hearted tilt gives you a stroke instead. Mario leaves the water at 42 units a frame upward, the same launch the code gives a standing single jump, with at least 15 units a frame of forward speed. He can grab a ledge on the way up, so a bank you cannot clear may still be one you can catch and climb.

That stick requirement is the whole trick. Press A at the surface with the stick neutral and Mario strokes along the top; press it with the stick forward and he heads back down.

Floating, sinking and the surface

• The surface is a lid. The code never lets a swimming Mario rise above 80 units under the water level, which is why he floats with his head out rather than climbing out.
• Near the top he drifts up; deep down he sinks. Within 400 units of that line, the water lifts Mario 1.25 units a frame. Deeper than that, a Mario who has stopped swimming sinks at 2 units a frame. The Super Mario Wiki's Swim page says Mario does not sink when he is not actively swimming, which only holds near the surface.
• The top 60 units heal. Once Mario is within 140 units of the water level, which leaves a 60-unit band at the top of his range, warm water adds 26 HP a frame, about a tenth of a wedge, so a nearly empty Power Meter is full again in under three seconds. Below that band the meter loses 1 HP a frame, one wedge roughly every 8.5 seconds. The health guide covers the rest of the meter, including Snowman's Land's cold water, which drains three times as fast and does not heal at the surface.
• The Secret Aquarium has no surface. The Super Mario Wiki notes there is nowhere to come up for air in it, and the level data agrees: the tank's collision tops out below its water level. Coins are your air supply in there, which is why the secret stars guide has you sweep its coin rings.

Currents: whirlpools, jet streams and the stream

The level scripts place four currents between them, and the collision data adds flowing-water floors in four more places:

Three rules from the code make those manageable:

• Currents only move a swimming Mario. The current code runs inside the swimming actions alone. Metal Mario walking the floor is not pushed, which is why the Dire, Dire Docks guide and the Jolly Roger Bay guide both send you through their jet streams with the Metal Cap.
• A jet stream outpushes Mario at its source. It pushes at 30 there, and his top swimming speed is 28. It weakens with distance, which is why the no-cap route the Jolly Roger Bay guide mentions exists, and why it is fiddly.
• The whirlpool loses to a good stroke. Its pull peaks at 20: stronger than a flutter kick inside roughly 800 units, weaker than a stroke at full strength. If it is dragging you in while you hold A, stop holding A.

The stream in the Cavern of the Metal Cap is the other number worth knowing. Its riverbed pushes at 28, Mario's top stroke speed, so swimming straight against it at full strength holds position at best. Go with it.

The Koopa Shell: eight seconds at top speed

Two Koopa Shells sit underwater in the N64 game, going by the level data and Ukikipedia's Water Shell page: one in Jolly Roger Bay, in the right-hand of the two clams below the cannon (the Super Mario Wiki says the other one holds a red coin), and one in a clam in the second area of Dire, Dire Docks. Wait for the clam to open, face the shell and press B. Mind the clam itself: the Super Mario Wiki notes that touching one while it opens or closes knocks Mario away for two wedges.

Once you have it, per the decompiled code:

• Mario swims at the 28-unit cap with no button presses. No rhythm, no strength to build.
• It lasts 240 frames, eight seconds, then the shell disappears and Mario drops into a flutter kick. At 28 units a frame, that is up to about 6,700 units of travel.
• B throws it, and a thrown shell is gone. So is a shell carried out onto land.
• It is not a weapon. Riding a shell on land counts as an attack; swimming with one does not, so enemies still hit you.
• No water jump while you hold it. The shell-swimming action never checks for one.

The music guide notes that swimming with a shell also cues the Powerful Mario music.

Metal Mario does not swim at all

With the Metal Cap on, the swimming actions hand Mario over to a separate set of metal-water actions, and the rules change:

• He sinks fast, at up to 18 units a frame.
• He walks the floor at about 21 units a frame with the stick fully pushed: quicker than a flutter kick, slower than a full-strength stroke.
• A jumps. If the jump carries him up near the surface, he leaves the water in a water jump that keeps his upward speed.
• Air does not drain and the surface does not heal him: the health code only touches a swimming Mario.
• Currents do not move him.
• When the cap's 20 seconds run out underwater, he goes straight back to treading water where he stands, with whatever meter he had, so finish the job somewhere you can surface.

The cap guide covers the green switch, and the Hazy Maze Cave guide covers the lakebed switch the Metal Cap is built for.

What changes on DS and Switch

The DS details are from the Super Mario Wiki's page for the remake. The version differences guide covers which build each release runs.

Mistakes that slow you down in the water

• Holding A to go faster. That is the flutter kick, and it settles at 12. Tap.
• Mashing A. A press early in a stroke restarts it and resets strength to 160.
• Waiting too long between strokes. If A is not down seven frames into the glide, strength resets. Press early and hold.
• Pressing A at the surface without pulling back. You get a stroke, not a jump.
• Treading water in deep water. More than 400 units below the top, an idle Mario sinks.
• Swimming into a jet stream at its source. It pushes at 30, and you top out at 28. Bring the Metal Cap.
• Throwing the shell away with B out of habit. Once thrown, it is gone.
• Looking for the surface in the Secret Aquarium. There is none; route through the coin rings.

Quick Action Checklist

• Tap A, do not hold it: let go during each stroke, then press and hold again as soon as the stroke ends.
• Aim for three strokes every two seconds, and listen for the stroke sound to change.
• Stick forward dives and stick back climbs; from level, Mario points straight up in half the time it takes to point straight down.
• To jump out, get to the surface, pull the stick almost all the way back and press A.
• Fall into deep water from any height without fall damage; dive in to keep pointing downward.
• Heal by bobbing in the top 60 units of warm water: a nearly empty meter refills in under three seconds.
• Grab the underwater Koopa Shells in Jolly Roger Bay and Dire, Dire Docks with B for eight seconds at top speed.
• Use the Metal Cap for jet streams: currents only push a swimming Mario.
• Outswim the Dire, Dire Docks whirlpool with strokes, not a flutter kick.