28.10.2024 – Deep

304.8 meters. That’s the deepest a human has gone underwater without a submarine. £04.8 meters with scuba gear. It’s a wildly long way. For the record holder (Ahmed Gabr), it took 10 years of preparation, 15 minutes of descent, and almost 14 hours of ascent!! For every 10 meters of descent, you gain 1 atmosphere of pressure. That means at 20 meters your body is under twice the pressure it is at the surface at 30 3x and so on. This pressure does things to your body, and that’s why shame had to come up so slowly to even it all out.

So what about whales? The sperm whales (Physeter macrocephalus) and Blainville’s beaked whales (Meslopldon densirostris) we saw today both dive over 1500 m deep, and to do so without a scuba tank, they do some amazing things. Their ear and nasal tissues are designed to fill with blood when they dive, protecting them from sinus damage and the dreaded “squeeze.” The blood vessels in these tissues may allow them to actively equalise their skins when diving. Their lungs (unlike ours) are collapsable, protecting them from damage when diving. This has further benefits, as when the lungs are collapsed, gas exchange stops, which prevents nitrogen absorption, thus reducing the risk of decompression sickness and nitrogen narcosis. However, despite these adaptations, ascent for these deep diving animals is still generally slow, and this is the reason their dives can take up to 2 hours.

By Peter Worth

Sightings of the day

Stenella

09:30 Bottlenose dolphins, Sperm whales

13:30 Bottlenose dolphins, Sperm whales

16:30 Sperm whales, Blainville Beaked Whales

Ribeira Brava

09:30 Bottlenose dolphins

13:30 Bottlenose dolphins