Dream Team Divers

Underwater Compass: Set It & Swim a Straight Line

Learn how to set your compass, keep the needle centered, and swim straight underwater. Includes an AOW skill section for 90° turns to make a square pattern.

Photo Guide: How to set the compass

Follow the steps below. Keep the compass level, use the lubber line (direction line), and keep the needle centered in the bezel marks.

Compass held flat and level
Step 1 — Hold it level
Keep the compass flat and level so the needle can move freely. Hold it steady in front of you where you can see it clearly.
Lubber line pointing in direction of travel
Step 2 — Use the lubber line (direction line)
Turn your body so the lubber line points exactly in the direction you want to travel. Your body, compass, and direction of movement should all line up.
Setting the bezel with the needle centered
Step 3 — Set the bezel (“red in the shed”)
Rotate the bezel until the north needle sits inside the bezel marks. This locks in your chosen direction.
Swimming straight while checking compass
Step 4 — Swim & keep the needle centered
Swim forward and make small body adjustments to keep the needle inside the bezel marks. Turn your whole body — not just your wrist.
Key rule to remember: The lubber line shows where you are going. The needle tells you if you are still going that way.

AOW Compass Skill: 90° Turns (Square Pattern)

Swim one leg, turn 90°, repeat to make a square. Keep the compass level, follow the lubber line, and keep the needle centered inside the bezel marks.

How to do the square (step-by-step)

1
Pick your leg length
  • Choose a fixed distance: 10 fin kicks, 15 fin kicks, or 30 seconds.
  • Use the same speed for every leg.
2
Set your first bearing
  • Face the direction you want to travel.
  • Point the lubber line (direction line) straight ahead.
  • Rotate the bezel so the needle is centered in the bezel marks.
3
Swim leg #1
  • Swim your chosen distance (fin kicks or time).
  • Glance every few kicks and keep the needle centered.
4
Make a clean 90° turn (right or left)
  • Stop, hover neutrally buoyant, and keep the compass level.
  • Right turn: new bearing = old bearing + 90°
  • Left turn: new bearing = old bearing − 90°
  • Turn your whole body until the lubber line points to the new bearing, then re-center the needle.
Wrap rule: if the number goes above 359, subtract 360. If it goes below 0, add 360.
5
Swim legs #2, #3, #4
  • Repeat the same distance each leg.
  • After 4 legs with 90° turns, you should end close to where you started.

Square helper (calculator)

Enter your starting bearing and choose left or right turns to get the 4 legs of your square.

Instructor tip: Have students stop and hover for 3–5 seconds at each corner before turning. It improves buoyancy control and reduces navigation errors.