The quick answer
Enter the cave on the islet southwest of Stillwind Slope. Swallowlight contains four side chests and a final treasure; the route deliberately drops through wooden floors before crossing moving and collapsing platforms.
On this page
Find the entrance at water level
From Stillwind Slope in Moonveil Mountain, head southwest toward the small island with the stone spire. Look for the cave near the waterline. Searching the summit puts you above the actual entrance.
Open the door with its lever, take the lift down and jump the first gap. Your main preparation is movement: settle the camera so the next landing is visible before stepping onto a platform that will carry you away.
First chest: the collapsing floor is the route
Near the spike trap, jump to the wooden floor across the gap. It breaks, dropping you to the lower route. Turn around after landing to collect the first chest.
Do not immediately try to climb back to the spike corridor. This fall is part of the route and puts the next opening beside the chest.
Second chest: opening, drop and boxes
Take the opening to the left of the first chest, jump across and continue to the next hole or breakable wooden floor. Drop below, then climb the stacked boxes to reach the second chest.
Open the barred door nearby to reconnect with the earlier chamber. This is a loop through the dungeon, so returning to a familiar room after collecting the chest is expected.
Third chest: cross the large gap
Enter the large chamber with moving platforms. Watch one complete cycle from solid ground, then use the platforms and thick rope route to cross. At the far end, descend on the moving wooden platform to the third chest.
A moving platform is a staging point, not necessarily a ride all the way to the next room. If it keeps turning back, inspect the rope and neighbouring landing instead of waiting through the same cycle indefinitely.
Fourth chest: open the upper gate
Step on the circular plate beside the third chest to open the overhead door. Jump up through it and cross the next suspended-platform section. Continue to the fourth chest on the higher platform.
The fragile platforms begin breaking after you land. Choose the next jump before touching down; save camera adjustments for solid ledges.
Final treasure and completion check
From the fourth chest, take the remaining collapsing-platform route toward the final chest. Recover your movement resources before starting that last crossing, then keep progressing between landings.
Open the final treasure and check the dungeon’s separate side-chest count. A completed final objective and four collected side chests are both needed for a full sweep; the first two are easiest to miss if you hurry back upward after the floor breaks.