To begin, slip the snorkel tube over the mount on top of the mask. The plastic tab on the snorkel tube should be facing behind the mask.

Once the tube hits the colored O-ring seal, gently push it forward while moving the tube side-to-side and pushing down firmly. Angling the tube is important so that it can work itself over the O-ring

Push firmly until the tube is flush with the mount on the mask. Do not use excessive force to install the tube. This tight fit helps prevent leaking while the mask is in use.