I read the book "Descent into Darkness". The author was a Navy salvage diver during WWII, and dove on the wrecks at Pearl Harbor. You needed nerves of steel to do this work. Yet he was deathly afraid of spiders. On one dive, he had to use a spare suit and helmet, while his was being repaired. After being lowered to the worksite, a spider suddenly appeared inside his helmet, and started crawling around. He was powerless to do anything about it. He panicked, and it nearly cost him his life.
"Yet he was deathly afraid of spiders. On one dive, he had to use a spare suit and helmet, while his was being repaired."
A spider in your helmet at depth is a bit different than a bug running across the floor.