Symmetrical brain coral “Diploria strigosa” has an emerald color
Prevent snorkel mask fogging. Get as little water in the mask as possible. Shake out any anti-fog or other water drops before using it. Try to have a relatively dry face. Once the mask is on with a good seal, try to keep from removing it and allowing moisture to enter. Try not to clear the mask by breathing inside of it unless you must (that adds moisture). We enter the water with a dry mask, over a dry face, and do not take that mask off at all during the snorkel, if possible. And it works.