When you take a selfie while wearing a snorkel, or while doing so.

When you take a picture of yourself using your smart phone while sneezing.

Snorkle+Selfie=Snelfie

When you take a picture of yourself (a selfie) whilst snorkeling, introduced by Victoria Justice on Instagram, recognized on The Tonight Show Starring Jimmy Fallon

A selfie that you send to someone via Snapchat.