"I've never been to Canada," I said in an annoyingly chipper tone.
"Is that right," the bored border guard asked.
"Now that you're here, what are you going to do?"
"SCUBA dive."
He sent me on my way after I assured him I had no alcohol, tobacco or firearms (we have a whole Govt dept for that, I told him) and he refused to stamp my passport.
This dive trip to the Thousand Islands in the St. Lawrence River was heavily hyped. Tons of incredibly well-preserved, old wrecks in fresh water with 40-100ft viz, just minutes from the dock, with only moderate current (when any). The caveat was that the river is actually just the top of Lake Ontario flowing to the sea. Even at the end of May, it would be Cold.
The diving delivered on the hype with one exception. The water wasn't cold. It was 10-15 degrees warmer than Dutch Springs (the large erstwhile quarry in Pennsylvania where we do training/practice dives). I didn't use my dry gloves. One guy used a wetsuit. We stayed in the Chalet Cabins, a diver-friendly set of circa-1950 cabins. I took a picture of the refrigerator and the clock radio perched on it.
There are quite literally thousands of islands. Nearly all are quite small. Maybe a few hundred feet square; some a quarter-mile. All are verdant and most sport living structures ranging from shacks to huge castles transplanted brick-by-brick from the old country. It is an exceptionally beautiful place.
Of seven dives, the most recent vintage wreck was 1932. We dove several very large (100ft+ long) wooden three-masted schooners that sunk over 100 years ago. They are completely intact. The masts have been broken, but are lying on/off the decks. You can swim through their cargo holds and check out the riveting. Almost unbelievable until you've seen them. Average depths ranged from 50 to 115 feet. There are hundreds of old wrecks along the river. Many are too deep for recreational divers. Even on these, though, you could execute technical penetration and deco dives. In fact, one instructor was guiding a student on his final deco dives.
But we also had some very new divers. They dove with single tanks. Not all used nitrox. They were in drysuits b/c of the advertised water temps, but with their dive runtimes, they could have gone wet. There were several rebreather divers as well. I was paired with one. He was using the rental unit for the first time post-cert. Even though he had a significant efficiency advantage, I managed to put him into a deco violation on our second dive. He was not completely familiar with the computer and didn't realize he needed a 2 minute stop at 10 feet.
The viz varied, but was never less than 40ft. On the Keystorm (a couple hundred feet long steel freighter sunk in the teens), we cruised around the upper half of the wreck. The wreck sits on its starboard side, gently sloping down the shoal that sunk it. The bow is at 28 ft and it runs down to 110+. We swum in the holds and through the large complex of the forward wheelhouse. We dropped over the port side to see the large gash made when it ran aground. It was about 20 ft long, but wasn't even big enough to stick an arm thru.
Our one night dive was a wooden fuel freighter that caught fire and exploded multiple times before sinking pre-1900. It was about 125 ft long and the hull is surprisingly intact given the fire. The twilight divers found a truly ripping current, but the night (barely 1.5 hours later) was mellow. The buoy is tied into a massive boiler the size of a house. It takes several minutes simply to swim around it. The wreck lies on its port side which is perpendicular to the current. In the main part of the hull, the current wants to push you against a motley collection of spikes and loose wooden boards. Our night dive didn't have much trouble with this. Without current, though, the swarm of fish dispersed. Wherever you shone your light there was a tangle of twisted metal, melted in the fire. A very haunted vision in our small lights.
The America was a traditional flat barge contracted to remove 20,000 ft of shoal on the side of a major shipping channel. An explosion sent it down next to the shoal in 75 ft. It landed upside down and scattered its tools, etc on the bottom (which you are repeatedly advised not to touch, b/c it is saturated with oil from the accident -- once on you, it's a bitch to remove). It was possible to swim under from side to side, but the clearance was tight, and we didn't want to risk the oil peril. There was some impressive boiler-like structure at the stern. And there was one more hazard.
Since we were right in the middle of the big shipping channel (as in for big ships), we had to keep an ear out for the tell-tale loud hum of such ships. These are container cargo and oil tankers of the sort that ply the oceans. They can push a 30-35 ft draught. That means you, on the wreck, are a mere 30-35 feet from their keel and, that's right, building-sized props. We were advised: a) not to be under the barge when one came along (you...won't like it), and b) hold on to the wreck for dear life and look up. You'll never get another view like that again.

Heh. Is that a promise?
Luckily we had no such encounters, but we did see ships that big, before and after the dive, go right over the wreck.