In a large bowl, mix together the vanilla cake mix, eggs, water, and oil.
Divide the batter between two bowls.
Mix a few drops of sky blue gel food coloring into one of the bowls.
Grease and flour a 7 inch bundt pan.
Pour half of the white batter into the bundt cake pan.
Drop scoops of the blue cake batter into the white batter.
Pour remaining white batter onto the blue batter.
Drop dollops of the remaining blue batter onto the top.
Swirl the two batters together without fully blending the two.
Add 1 cup water to the inner bowl of the instant pot. Place the trivet inside.
Make a foil sling and carefully lower filled bundt pan on top of the trivet in the instant pot.
Loosely fold foil sling over the top of the bundt pan.
Close lid and set to sealing.
Cook on high pressure for 35 minutes.
Quick pressure release.
Let cool on a cooling rack for 30-60 minutes.
Use a knife to gently separate the cake from the sides of the bundt pan and empty the cake onto a plate.