Run left-to-right in the room below using SpeedBooster, and jump up through the door. Hold left through the transition to avoid hitting the crab.

Entrance condition:

{
  "comeInWithPlatformBelow": {
    "minHeight": 9,
    "maxHeight": 10,
    "maxLeftPosition": -38.5,
    "minRightPosition": -7
  },
  "comesThroughToilet": "any"
}

Requires:

"canCrossRoomJumpIntoWater"
"SpeedBooster"

Dev note: This strat is applicable in Crocomire's Room and the Post Crocomire Jump Room. Sufficient vertical speed could be obtained with fewer tiles, but it would require jumping further to the right (i.e., increasing minRightPosition) which would not work in PCJR unless the PB blocks are broken.