|Adjacent rooms||Mt. Everest
To get the missile pack, the optimal shinespark is along the floor, but this is a very difficult short charge, requiring a stutter-3, or a 4-tap.
Slightly slower is to go up to the platform with the door to Fish Tank, and do a 2-tap. A 1-tap will also work, but the spark would need to be charged very late on the platform, so a 2-tap would be more comfortable for most runners.
The spark can be lined up using either the 3-leaf plant on the ground, or by brushing up against the right side of the bottom-left floating platform.
Without short charging, this requires starting a charge in Crab Tunnel, but many people find this more difficult than the 2-tap on the platform above, because of the door transition being in the middle of the maneuver.