Anti-fog
Sometimes the factory-applied anti-fog coating needs to be activated. If a new pair of goggles turn blurry after a few minutes of swim, submerge your goggles in water, then let the water drain. Next, smear the inside of the lenses with your soft fingertip (avoid touching with finger nails). After swiping the wet lens 3-10 times, the lens should feel a bit slippery, and should not fog. If the lenses are not slippery at all, the original anti-fog coating has worn off. After the original anti-fog coating is gone, you can use baby shampoo or a commercial anti-fog product to keep your lenses clear.
DIY anti-fog solution application bottle
Add 2 small drops of baby shampoo, fill not-quite-full with drinkable water, and mix gently. Squeeze the sides of the bottle to get liquid to come out as you gently smear it over the surface of the lens with the sponge tip. Don’t press the sponge tip down hard onto the lens since the plastic part that holds the sponge could scratch the lens.