Pearls are a new resource in Animal Crossing: New Horizons that you need to craft the summer update's new mermaid-themed DIY recipes. They are also extremely rare, and so far there are only two official ways to actually get them.

How To Get Pearls In Animal Crossing: New Horizons

1. Diving To The Ocean Floor - While swimming in the ocean, just dive down when you see columns of bubbles rising to the surface and chase the deep sea shadow until you catch something. More often than not, you will come up with one of the 40 new sea creatures added in the new summer update, but if you're super lucky, you might find a pearl.
2. Trading Scallops With Pascal - Pascal is a recently-arrived visitor who will appear once a day when you dive down and find a scallop, though not always on the first scallop. He will offer to trade you for it. Most of the time, you'll get a mermaid DIY recipe or mermaid clothes, but sometimes he will gift you a pearl. The rate that he gifts pearls over mermaid recipes and clothes is still unknown.

These are the only official, confirmed ways to get a pearl in Animal Crossing: New Horizons right now. Neither of these methods require any special tools, but you will need to purchase the wet suit to start swimming and diving, as the only place you can find pearls is in the ocean.

Farming Or Grinding For Pearls

There's no official way to farm pearls or grind for pearls in New Horizons that doesn't require "time traveling," or adjusting the system clock on your Nintendo Switch to force-skip days. If you decide to time travel, the only possible way to get more pearls would be to grind for sea creatures until you get your daily Pascal encounter.'