It’s no fun diving with a mask that keeps filling with water every few seconds. So the first consideration when buying a mask is how well its skirt seals against your face. Despite claims to the contrary, no one mask fits all. While the vast majority of mask skirts range from four and a half to five inches in width between temples, their shapes differ considerably. So the only way to find the right mask for your face is to try them on. Note: don’t forget to take a reg or snorkel along to see how well the masks fit your face when it is distorted by a mouthpiece.
Step 1: remove the strap or adjust it as loose as possible so it’s not doing anything. Water pressure, not strap pressure, is what should seal the mask to your face.
Step 2: making sure no hair is under the skirt, put the mask on your face and move it this way and that until it feels centered, comfortable, and all edges of the skirt are in contact with your face.
Step 3: with a snorkel or reg in your mouth, suck gently through your nose and let go of the mask. If it has made a good seal it will stick to your face for a couple of seconds. Don’t suck too hard; that will just distort the skirt and give it a false seal. A properly fitting mask will seal with a gentle touch.
Step 4: adjust the strap so the mask is just barely held in place against gravity, not pulled tight, and try Step 3 again. Sucking should pull the mask toward your face. Hold your breath. The mask should stay pulled in for several seconds—the longer it stays, the better the seal.
Buying your first mask? Check out our Mask, Fins and Snorkels Gear Guide.