Freediving Fun Ideas

[Jellythings]

A local lake has some neat stuff at 30'. A wooden platform, hoops, bicycles, boats and all kinds of general things to look at while you're down. I want more things to "do" while I am down there.
The only idea I am coming up with is to install one of those chess sets that are made of granite or glass or something heavy like that. I'd like to setup target practice for spearfishing but think folks around the lake would get a little cranky seeing spearguns going down in there.
Does anyone have any ideas about what would be some really nifty "freediving fun" things to have and do underwater?

 

[Manny_OCF]

I recently recreated the egg cracking experiment. A team of scuba divers went down to 30m, and cracked an egg, showing how the pressure keeps the yolk in place.
I went to my local dive site (though its only 12m) and did the same, it was fairly cool seeing it float around.
My friend and I took turns, and also practiced our breath-holds during this time