Elements · LEVEL 21 · Verified walkthrough

The Rolling Reservoir

Send the original ball through the coloured relay. Fireboy holds Yellow while Watergirl releases Purple and holds Cyan; then lower Red, White and Green so the ball can hold Blue for both exits. Collect all eight diamonds along the way.

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Level objective

Bring Fireboy to the orange exit in the lower left and Watergirl to the blue exit in the lower left. Both heroes must be at their own doors together. The 8 unmarked diamonds are optional; collect every diamond for a perfect clear.

The Rolling Reservoir, elements level 21: actual game view with Fireboy, Watergirl, diamonds, elemental pools, matching exits, and this level’s mechanisms.
The level at its starting positions. Orange is safe for Fireboy; blue is safe for Watergirl; purple goo is dangerous to both.
Level at a glance
CampaignElements · 21 of 39
Collectibles4 fire diamonds, 4 water diamonds. 0 marked diamonds required; 8 optional.
Hazards6 water pools. Only your own element is safe; purple goo is dangerous to both.
Mechanisms7 plates, 7 moving platforms, 1 rolling stone
Win conditionBring Fireboy to the orange exit in the lower left and Watergirl to the blue exit in the lower left. Both heroes must be at their own doors together. The 8 unmarked diamonds are optional; collect every diamond for a perfect clear.
ExitsFireboy: lower left. Watergirl: lower left.

Step-by-step walkthrough

  1. Collect the high right diamonds

    Fireboy walks left from the start and jumps right onto the first wall ledge. From its left end, jump up before steering right onto the higher ledge and collect the red diamond. Watergirl follows onto the first ledge for its blue diamond, then returns left to the main ramp.

  2. Reach the middle red diamond

    Fireboy jumps left from the high right ledge onto the small upper shelf. Walk off its right end onto the main ramp, return left and jump across the small water pool from its dry right bank. Continue left to the red diamond on the raised middle shelf.

  3. Cross the upper water

    Watergirl climbs both right ledges, jumps left onto the upper shelf and walks left through the upper water for its blue diamond. Leave her on the dry bank at the pool’s left end.

  4. Hold Yellow first

    Fireboy leaves the middle shelf to the left, descends the far-left ramps and follows the lower slope right to its red diamond. Jump from the slope’s right end to the middle island. Stand on the yellow plate. Keep holding it while Watergirl starts the ball.

  5. Release the ball with Purple

    Watergirl jumps left from the upper pool’s dry bank onto the middle shelf, then jumps left again to the high left platform. Stand on Purple until its horizontal panel slides aside and the ball falls onto the shelf below.

  6. Start the ball rolling right

    Watergirl steps off the high platform to the right and lands to the right of the ball. Jump back over the ball, land on its left and walk right to give it a gentle push. Jump onto the raised middle shelf before the ball enters the narrow tunnel.

  7. Hold Cyan for the first relay

    Watergirl follows the main ramp right to the cyan plate and holds it. Fireboy stays on Yellow. Wait for the ball to roll through the narrow passages, cross both lowered connections and reach the far-right red catch.

  8. Prepare Green and the remaining blue diamonds

    Watergirl leaves Cyan, returns left to the middle shelf and jumps off its left end. Descend the far-left slope, then jump right to the yellow island for its blue diamond. Walk off the island’s left end to the lower passage, collect the low blue diamond and stand on Green.

  9. Reach Red with Fireboy

    Fireboy leaves Yellow to the left, drops into the lower passage and moves right. Jump across the central water to the dry white plate and collect the red diamond above it. Move to the near edge of the next water pool, jump right under the low roof and stand on Red.

  10. Hand the ball from Red to White

    Keep Red pressed until the ball has descended and rolled left clear of the red panel. Fireboy returns to the very edge of the water’s dry right bank and jumps left under the low roof. Continue to White and hold it before the ball reaches the gap below.

  11. Let the ball hold Blue

    Keep Fireboy on White and Watergirl on Green. The ball rolls left over both lowered panels and down the final slope onto Blue. Wait for the blue exit gate to finish lowering. The ball stays on the plate while both heroes leave their controls.

  12. Enter the matching exits

    Watergirl walks left through the open blue gate into her door. Fireboy jumps left across the central water and follows the lower passage into his red door. Either hero may enter first.

This route was verified in the game simulation using player controls, required diamonds, and both matching exits. It describes this version’s independently reconstructed room, not an official walkthrough.

How this room’s mechanisms work

  • Switch 1

    middle center

    Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.

    Controls Moving platform 6.

  • Switch 2

    middle center

    Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.

    Controls Moving platform 1.

  • Switch 3

    lower center

    Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.

    Controls Moving platform 4.

  • Switch 4

    lower right

    Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.

    Controls Moving platform 3.

  • Switch 5

    lower center

    Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.

    Controls Moving platform 5.

  • Switch 6

    lower left

    Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.

    Controls Moving platform 2.

  • Switch 7

    upper left

    Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.

    Controls Moving platform 7.

  • Moving platform 1

    middle center

    At least one of these inputs must be active: Switch 2.

    When powered, it moves right; when power is released, it returns.

  • Moving platform 2

    lower left

    At least one of these inputs must be active: Switch 6.

    When powered, it moves down; when power is released, it returns.

  • Moving platform 3

    lower right

    At least one of these inputs must be active: Switch 4.

    When powered, it moves down; when power is released, it returns.

  • Moving platform 4

    lower center

    At least one of these inputs must be active: Switch 3.

    When powered, it moves down; when power is released, it returns.

  • Moving platform 5

    lower center

    At least one of these inputs must be active: Switch 5.

    When powered, it moves down; when power is released, it returns.

  • Moving platform 6

    middle center

    At least one of these inputs must be active: Switch 1.

    When powered, it moves down; when power is released, it returns.

  • Moving platform 7

    upper left

    At least one of these inputs must be active: Switch 7.

    When powered, it moves right; when power is released, it returns.

  • Rolling stone 1

    upper left

    Push from the side to start it rolling. Slopes and gravity then guide its motion.

    A rolling stone can hold a pressure plate. Follow the walkthrough’s order before releasing stones into their channels.

If you get stuck

Check the unfinished objective

The diamonds in this room are optional. If you only want to finish, bring both heroes fully inside their own matching doors.

A gate or platform moved back

A pressure plate releases when its rider or weight leaves. Keep your partner on it until you are safely across. Levers stay set after you leave; check their ON or OFF state before crossing.

You missed a moving platform

Return to safe ground and use the connected switch to bring it back. Board before your partner releases the plate or changes the lever. Avoid jumping into its underside; line up with the open shaft first.

You cannot recover safely

Pause and choose Restart level to reset both heroes, diamonds, weights, and switches. Previously completed levels stay saved. Follow the step order before moving a box or releasing a weight.

For touch controls, jumping, audio, or online connection problems, see player troubleshooting.

Level questions

How do you finish The Rolling Reservoir?

Send the original ball through the coloured relay. Fireboy holds Yellow while Watergirl releases Purple and holds Cyan; then lower Red, White and Green so the ball can hold Blue for both exits. Collect all eight diamonds along the way. Bring Fireboy to the orange exit in the lower left and Watergirl to the blue exit in the lower left. Both heroes must be at their own doors together. The 8 unmarked diamonds are optional; collect every diamond for a perfect clear.

How many diamonds are required in The Rolling Reservoir?

8 diamonds: 4 for Fireboy and 4 for Watergirl. None are required to finish. 8 unmarked diamonds are optional collectibles for a perfect clear.

Which hazards are in The Rolling Reservoir?

6 blue water pools (upper center, middle center, lower right, and lower center). Watergirl can enter blue water; Fireboy must avoid it. If either hero falls into a dangerous pool, both players restart the level.

What do the switches do in The Rolling Reservoir?

Switch 1 (middle center): Controls Moving platform 6. Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it. Switch 2 (middle center): Controls Moving platform 1. Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it. Switch 3 (lower center): Controls Moving platform 4. Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it. Switch 4 (lower right): Controls Moving platform 3. Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it. Switch 5 (lower center): Controls Moving platform 5. Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it. Switch 6 (lower left): Controls Moving platform 2. Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it. Switch 7 (upper left): Controls Moving platform 7. Keep a hero or movable weight on this plate to keep its signal active. Stepping off releases it.