Dolphin mono-fin swimming

Fin swimming is an interesting and fast swimming sport.
Today I stumbled upon this (for me new) fin which completely fits in my own line of designs (dolphin fin page)

Dol-fin orca.

Interesting youtube movies
150m dynamic
 clear water

Dolphin bubble rings

Dolphin bubble rings.

Blowing bubble rings is do-able but not easy, but what dophins can do with them is amzaing, what control!

Dolphins on
youtube1
youtube2
 Obviously the dolphins re-energize the bubble rings through the pressure wave in front of their domed skull.
Will try that next time in the pool, although I will have to find something larger than my own skull to produce this pressure wave.

A kid blowing rings in a pool also on youtube