The BBC has some good aerial video of narwhals navigating through cracks in the Arctic sea ice on their summer migration. You can see it here.
About Neil Hambleton
I am a British Sub-Aqua Club (BSAC) Advanced Diver and an Open Water Instructor. I have been diving since 1992, after joining South China Diving Club (SCDC), which is a Hong Kong-based branch of the BSAC. Having moved to New Zealand, I am now a member of BSAC New Zealand.