Place the whole squash in the microwave. Heat on high for about 5 minutes, until the shell is softened enough for a knife to get through it. Halve the squash lengthwise.
Place the trivet in the Instant Pot.
Add the water to the pot, and place the squash halves on top of the trivet, cut side up. Sprinkle the squash with salt and pepper.
Close lid, and set valve to sealing.
Cook on high pressure for 13 minutes.
When the cooking time is up, quick release the pressure.
Remove the squash from the pot. You can remove the peel using a paring knife or by scooping the flesh out of it with a large spoon.
Serve hot or refrigerate and save to add to other dishes.