This thing looks like a blast. Make a cheaper plastic version for $300 and I'm sold.

This is an awesome idea I want to try it for sure.

What !!! I was doing this 5 years ago when I worked on yachts as a liveing. All we used was the washbourds ( removable , sliding door ) of the yacht and a 50 ' mooring line. It worked fine and it was free . What is the nest thing that is going to be re done that is all ready free on a boat? Bilge bording . Wiith a $300 price tag. Nice try all the same but far to costly when it is free or other wise a small bit of plywood and rope works v well. Simon

Shark bait!

I like it.
Two suggestions: 1) There does need to be an alarm so that the boat driver can stop if the diver lets go. Since the towline tension will decrease radically when the diver lets go, a fairly simple mechanical "flag" could pop up when towline tension decreases. Fancier audible alarms would be even better and enable this thing to be fairly safe.
2) Since there's a towline from the surface, it wouldn't be too hard to have a flexible air-suply tube running down to an air-mask. That would enable the diver to stay down having fun indefinitely : )

Looks like a fast way to tear up a coral reef. Not all ideas are good ideas. Murphy's law dictates that if something bad can happen then it will.

Just use a water skiing tow rope and swim fins.

great concept...but its already been done...we had something similar growning up as kids...and that was over 45yrs ago...Im sure that this is much more technical than our fun ole porpoise board...that our uncle made for us out of a block of wood...with 2 handles ..retro is new...Im guessing...but using this with the liquid image underwater googgles would give some great footage...

Ummmmmm - going a bit mad here.... ancient memories.
There was a movie about sponge divers from Greece in an OLD black and White movie.....
On a set of steel rods with control surfaces - being towed behind a boat... something like the front end of a U boat - minus the U Boat.
I think it was either this one, or the following.
Beneath the 12 Mile Reef (1953)
Boy on a Dolphin

Hmmm. I'm 54 now and was doing that when I was a teenager, with two bits of wood. You'd have to be dumb to pay that kind of money.
To Denis Klanac in an earlier thread, You'd have to be pretty dumb to be any where near sharks if your doing this.