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Jump through the door in the previous room, and perform an air ball soon after entering. With a last-frame jump through the door, there is a wide timing window to do the air ball. With an earlier jump through the door, the airball must be done more precisely: in this case buffer aim-down through the transition and morph immediately on entry, in order to conserve momentum while contacting the overhang.

Entrance condition:

{
  "comeInJumping": {
    "speedBooster": "any",
    "minTiles": 1
  }
}

Requires:

"canCrossRoomJumpIntoWater"
"canLateralMidAirMorph"
{
  "or": [
    "canTrickyJump",
    "canMomentumConservingMorph"
  ]
}

Clears obstacles: door_1

Dev note: There is a 4-frame window for the jump that can work; jumping in the later part of that window is better as it gives a bigger window for the morph. In water physics, an airball has higher base speed ($1.8) than spin jump ($1.6) or aim down ($1.4), which is the other reason why doing it early helps, in addition to how it helps clear the overhang. Doing a ceiling mockball at the top of the room can also work, but it is more difficult, and the frame-perfect jump is required in that case.