Does the Type of Dive Mask Matter to a Shark?

Abstract

Eye contact with a shark is a crucial element during an interaction with a diver. Different mask frames change the size of a diver’s available field of vision, and so make a person’s eyes unequally visible from different angles, particularly when comparing mirrored to regular glass. This study examined whether it matters to a shark if it can see a diver’s eyes when getting closer. The test-subjects changed masks in a random, timed routine, while the relative distance, the absolute distance between a shark and diver expressed in a fraction of the shark’s body length, between approaching shark and human was tallied. Sharks came significantly closer (p = 0.0139) when a diver’s eyes could not be detected, showing that they orient themselves and approach based on the human’s eyes. Given that human comprehension of sharks is rudimentary, every possible benefit, even a minimal one like choosing the most optimal mask, is recommended whenever approaching sharks are likely to be encountered.