Level 4 · Legends of the Deep

Mission 323

The Plumber’s Trick: An Airlock That Never Leaks

Badge: Master Plumber

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Dig a U-bend tunnel under the dome wall so you can swim in and stay dry.

No more climbing the snorkel. You need a front door under the sea… that the sea can't get through.

  • New skill Building a U-bend water lock
  • Level 4 · Legends of the Deep
  • Difficulty Intermediate
  • Mode Survival
  • Time 30–45 min
  • Ages 13+

What you’ll build

You need a front door under the sea that the sea can't get through. Sketch a U-bend, dig down inside the dome, tunnel under the wall and then up to the seafloor. Add ladders and a trapdoor, then time your swim in.

Finish line: Your U-bend airlock lets you swim into the dome and climb out dry, with no water following you in.

Bonus challenge: Build a second, sneakier entrance on the far side, hidden behind a wall of kelp. Can anyone find both doors?

You’ll need

  • Ladders
  • A trapdoor
  • A pickaxe
  • A shovel
  • A stopwatch

You choose

  • My airlock's name
  • Secret marker for the outside door
  • My bet: will any water get in?

Stuck?

  • Dome flooding? The tunnel must dip below the dome floor; water spreads sideways and down but never up.
  • Ladders won't place? They need a solid block behind them.
  • Can't find the door at night? Mark the outside entrance with something bright.

For grown-ups

Get this mission

This mission is in Mission Pack 32 (Level 4: Legends of the Deep). Its printables arrive in the store soon. We release about one level a month.

Print one mission at a time. You never need to print everything.

Played on Minecraft Bedrock on iPad. Buttons can differ on other devices and versions.