a dolphin or whale
Whales.
whales for 20 hours
David Blaine's current record for the longest breath hold is 17 minutes and 4.4 seconds.
The Cuvier's beaked whale holds the record for the longest recorded dive of any mammal, staying submerged for up to 138 minutes.
Overall, studies have been done with many animals and the current record-holder is the loggerhead musk turtle, which has been found to be capable of holding it's breath for more than 5,000 hours during forced immersion. That's 208 days, folks. They can absorb oxygen from the water through their skin.
The record for the longest time wearing a hat is 1 year, 283 days, achieved by Odilon Ozare from Brazil in 2016.
The Bowhead whale is the longest living mammal.
Narwhal.
I don't know how long YOU can hold your breath under water but at 2008, a man named David Blaine broke the world record for holding his breath for seventeen minutes and four seconds underwater.
In 2007 Lithuanian Arvydas Gaiciunas claimed a new world record for holding his breath underwater: 15 minutes, 58 seconds.
They breath air
Yes