Swimming is critical to most out of bounds glitches in this game.

If Fox enters and exits a plane of water without colliding with ground, he will continue to swim at that plane level, even beyond the bounds of the water. Normally the game prevents this by ensuring that all water is encapsulated by land, but there are OOB glitches that get around this.

Fox lacks the ability to dive, but there are a few known methods for controlling swim height outlined in this guide.

#All Water Plane Heights I've recorded the heights of all water sources in the game. Here is a spreadsheet of all water plane heights in SFA

Most water planes are flat, but there are some notable exceptions. This is not yet fully understood. For example, performing an air-swim from the waterfall in ThornTail Hollow can result in a swim height between -645 and -646.5 (as far as I know). This small difference can actually make or break some tricks -- for example Dark Ice Mines Early (DIME) needs this number to be as close as possible to -645, or the glitch does not work.

Swimming near a different water plane will cause Fox to switch to that plane. To travel upwards, the new water plane must be within 116 units To travel downwards, the new water plane must be within 125 units

Technical Information

Depth != PlayerY. The player will actually be 21 units above the surface depth. The player also oscillates by about 2 units up and down constantly (+/- 1 unit)

When standing on land, the game registers Fox as having a swim plane of depth -100,000. Simple memory scanning can be used to find this value.

• If using Dolphin Memory Engine, a float scan can find these values.
• If using Cheat Engine, this requires scanning for Big Endian Floats. See https://forum.cheatengine.org/viewtopic.php?%20t=551054

Swim Cancelling

There are three known ways to cancel a swim:

1. A collision cancel. If Fox's feet collide with anything that can be stood on, the swim is canceled.
2. An item discovery prompt cancel. If Fox is outside water and picks up an item for the first time, the discovery prompt will end the swim. An old TAS Any% route used to do a Fuel Cell cancel to collect K4.
3. A cutscene cancel. Some cutscenes, such as the sewer switch change cutscene, cause Fox's swim to cancel. Not all cutscenes do this. For example, the Tricky color change cutscene does not. Also, some cutscenes will warp Fox, canceling the swim.

Height Control Methods

There are a few known methods for controlling swimming height within a water plane.

Ceiling Collision

Normally, Fox cannot be pushed downwards once he rises to the top of the water plane. However, if Fox never fully reaches the surface, it is possible for him to collide with a ceiling and be pushed downwards.

This technique is not used in the current route.

Underwater Staff Swinging (TAS Only)

Underwater Staff Swinging (USS) is an incredibly useful trick.

USS allows Fox to be registered to a certain swim plane, but drop down to his current sub-plane height (see the sub-plane section below for details). This essentially allows fox to "dive" to sub-plane levels, and re-emerge when convenient.

This used to be the only method for obtaining K4 early, but we have since found a better setup using Memory Leak. USS is still used in the "No Void Traveling" TAS route to obtain Ground Quake Early.

Requirements to start the trick:

• Fox must be able to stand adjacent to the body of water.
• Fox must be able to swing his staff into the water without the staff colliding with an object. This swing must bring Fox far enough into the water such that the game considers him swimming.

Requirements to sustain the trick:

• Fox must ALWAYS be moving in any direction. The trick does not work if standing still.
• You must swing within a 4 frame window to start the next staff swing. Missing this window will cause Fox to start swimming, cancelling the trick. A human can do this for a few swings, but not for the continuous 2m 30s required for K4 early. Turbo controllers can work too (but are not accepted in Any%).

Example 1) Getting into the K4 room. This trick uses underwater staff swinging, a sub-plane transfer (to lose height, preventing a water-plane transfer to the river), and a Fuel Cell discovery swim-cancel to complete the trick (not shown in video).

Example 2) TAS only Cape Claw OOB. This trick does an incredibly long underwater swing sequence, followed by a collision cancel. This trick is not used in any route.

Sub-Planes

A strange mechanic we have uncovered is that Fox will "sink" to a special sub-plane in certain situations.

Sub-planes are dependent on the terrain above them. They are ALWAYS lower than the terrain (we have yet to find an exception to this).

Example 1) If you perform Cape Claw Early without Tricky, the intro cutscene in Cape Claw will glitch. This causes Fox will fall through the floor forever. However, if you walk forward and press Z to zoom at the exact right moment, Fox will stop falling. The height at which this is possible is the sub-plane.

Example 2) If you perform DIME to get to SnowHorn wastes before obtaining Tricky, and kill the 3 SharpClaw by the scarab bag mammoth, Fox will fall as before after a short delay. If Fox aims with Fire Blast and does not release (not shown in video), he will sink to the exact height of the sub-plane.

Sub-planes are important for understanding underwater staff swinging.