I'm looking for something I can ride on the lake that works the same
muscle group as riding a bike on the road. Basically I want to train
for a bike ride at the lake without having to ride on the roads there.

I've found a couple products out there and was wondering if there were
any opinions on these or other products I should look at.

1. Hydrobike - basically a bike frame mounted on a couple of pontoons,
single gear, I actually rented one of these and found it slower than I
expected. Steering is via a blade mounted on the end of the front
fork.
2. Seacycle Waterbike, more of a recumbant setup, you lean to steer
this one.
3. Shuttle bike, you attach 2 inflatable pontoons to a frame and the
frame gets attached to your bike. Provides all the gearing available
on your bike.

Of course faster is better, but I'm really looking for something I
would enjoy riding for 1 - 2 hours.

thanks...Chris