freediving

US /ˈfriː.daɪ.vɪŋ/
UK /ˈfriː.daɪ.vɪŋ/
1.

lặn tự do

the activity or sport of swimming as deep as you can under water without using breathing equipment:

:
In freediving the diver descends with no more than a lung full of air, to depths of up to 100 meters.