ok, about 2 months ago, i waswatching a show on tv called Dirty Jobs. and there was an episode about shark attack/defense. they did a story about a group of scientists in bimini and the florida keys who did a study based on the old sailor myth that 'if you drag a dead shark behind your boat, other sharks will stay away. turns out it is true! they actually grind up certain parts of sharks and use a chemical process to extract the "essence" of shark . they then deploy" grenades" containing the agent around swimmers in the bahamas during a feeding frenzy (reef sharks 5 to 9 ft long) almost within 3 to 5 seconds ALL the sharks leave the area! ALL of them. it is amazing! well, as it turns out, 2 of the three scientists are really good friends of a buddy of mine. and i have been at a barbeque at on of their house already. basically i know these guys. i was telling my buddy about this cool thing i saw on tv, when he pointed out that the guys i saw on tv was eric and dr gruber. i was FLOORED. and they were on there way over. so last night i talked to eric at great length about it. they have a fledgling company called sharkdefense.com check out this website. the grenades are 35$ each, you can carry them on a float. it is a litttle smaller than a can of soda. you activate it and it starts slowly sinking while spoinning around emitting a yellow cloud. the sharks get one whiff of this and they bolt! leave the area all together! eric was telling me the most amazing thing about it: the other fish LOVE THIS STUFF!!!! its crazy! they took it to panama to the yellowfin tuna pens. to demonstate it to the fisherman. right now they are working on a slow dissolving version to put on fisherman long lines to repel sharks and improve catch. to do this , they have to demonstrate that it wont rpel the tuna as well as the sharks. well, as it turns out, thetuna hit the baits treated with the gel at almost 20% MORE than the untreated baits!! he then took the stuff to the university of miami cobia tank,(250 cobia kept in a huge tank) the results were amazing. the cobia were all over the baits that were treated. so eric was pointing out the multiple uses for the product, but he never thought of freedivers. we constantly see sharks. and are always at risk, since we swim in our own chum slicks behind the boat. well he is going to give me a bunch of gel to mix in with the chum. plus i will be keeping a few grenades on my float while in the blue water from now on. the current version deploys at the surface, slowly sinking while spinning and dispersing a cloud and it slowly sinks to around 10 ft and then as it empties and becomes lighter slowly comes up and flots when empty. they are not designes to dploy at depth. he said the pressure outside doesnt allow the stuff to escape the can. they charge them to 30psi. if i want , he said, he will make me a batch that will work, they already tested it at depth , it works fine, you just have to charge it to 80psi and it works good. i figure we could put some gel in the sand ball chum balls we drop on wrecks. maybe even drop a weighted grenade to clear the area of sharks and put the fish in a frenzy. then drop in for some shark free killing. cool stuff, check it out. shark defense.com