My recommendation is to use the salvage operation mission type since it makes the whole thing much easier to do.

• Azure Weald biome;
  
  
• Mobula Cave Angels spawning.

Step 1:
Find a hole in the ceiling. Sadly resupply pod made holes or the ones made from lithophage warnings do not work - that's where the already dropped down rescue pod in salvage operations work;

Also, the opening above the rescue pod has no ceiling collision - you won't get stuck when going up for a long while (I got up to 500 meters above the drop pod got bored since nothing was changing at that point)

Step 2:
Catch a Mobula Cave Angel;

Step 3:
Fly in circles up the cave opening upwards till you magically appear out of bounds. Do not just fly up. Since the Cave Angels don't fly only upwards they will hit a wall. If you hit a wall or brush against one for too long - you will fall down and have to repeat the whole process.

Step 4:
Success

Step 5:
Press 'h' for long to disable hud and make some pretty screenshots for yourself.

• Please, don't do this in a multiplayer game with random people unless you all agree to that - otherwise it can ruin the fun (First your assignment, only then your excitement - don't be a douche)
  
• If you want to go back you don't have do drop down the way you came from - any map border works since you will just clip back - watch out for fall damage!
  
• Have fun with it! If you find something unexpected I am more than excited to hear about it in the comments.