Ocean water bakes on a toaster tray in the sunlight. The Sun does its invisible work little by little. A few days pass. The water is gone. What’s left behind? Salt! Brian McMahon is harvesting it while he’s on vacation. Whenever he travels to a new place, he dries seawater and collects its salt. He learns something surprising. Salts from different oceans have different textures and flavors.

Mr. McMahon uses his salt-making skills to build a business. Now he and his wife own Hatteras Saltworks. Their home is on Hatteras Island, North Carolina. Clean ocean water surrounds them. Two strong ocean currents—the Labrador and Gulf Stream—meet near their home. So nutrients and minerals from the far reaches of the Atlantic Ocean are mixing together there. Brian collects sea water in tanks at high tides on full moons. Water is saltiest then. He filters out sand and other impurities. Instead of toaster pans, he stores the seawater in evaporators he built from recycled parts. The North Carolina sun bakes through their tops—old windows. Temperatures inside rise as high as 180 degrees. That’s hot enough to kill bacteria. After about a month, nothing remains but white, fat, zesty flakes of salt.

Regular table salt is often mined out of the ground. Sea salt is less processed. It retains more minerals, which people value for taste and health benefits. Sea salt doesn’t need additives to keep it from clumping like table salt does. A gallon of seawater produces about four ounces of salt. (That’s a little heavier than a deck of cards.) The McMahons crush the sea salt into smaller grains and package it. Hatteras Saltworks offers three flavors—pure, smoked pecan, and rosemary.