潜る has two possible readings: もぐる and くぐる. The first is used when you mean to dive underwater or go underground. The second is used when you pass through or under something, sometimes with difficulty, such as crawling under a fence. We want you to focus on もぐる, so here's a mnemonic to help you:
Why are you trying to dive underwater again and again? It's to get mo' goo (もぐ) to sell on the black goo market. Who knew that sea goo was such a commodity?
I saw a mole going underground.
How long can you stay underwater?
My dog learned a trick to jump through a hula hoop.