The Old China Hand is located on a wooden pier at the far end of the left canal. To reach it, take an immediate left when coming from the Luminous Path Compound and Buddhist temple. There should be several signs on the way there.
In the bar, there is an unnamed woman, man, drunk boatman and bartender. The man will approach JC thinking he is Paul Denton, then cut the conversation when he realizes the mistake. JC can persuade the man that he is Paul's brother by talking to him a couple of more times. After that, the man will offer JC a few items for sale, most notably the blueprints of the VersaLife facility for 2000.
JC can also start an unusual conversation with the boatman. The Bartender, who heavily resembles Isaac, will sell JC consumables and give small-talk. Some items of use can be found in the kitchen.
The Old China Hand is the only way to get into the collapsed Canal Road Tunnel. To reach it, climb the crates in the meat locker, then crawl across a girder to reach an air vent (this is fairly difficult, as the floor in the freezer is slippery). Once in the air vent, there is a fairly linear route to the tunnels.
Once JC enters the tunnels, he can see two crates holding rebreathers trapped under several pipes. To reach these rebreathers, exit to the Canals, and swim through one of the smaller tunnels. In the middle, on the floor there is a small hole which can be crawled into to reach the crates.