score:3
Not, that is impossible. Even back then. Every ship needs two items to sail:
Without all of the above a ship is not allowed to sail. Those documents are checked in every port, no matter what.
It goes a bit further. You can't embark or disembark where ever you want. Passengers (and/or crew) can only embark/disembark in ports with custom/immigration facilities. Nowhere else.
Supposing a captain dumps his passengers somewhere in the middle of nowhere? That happened during the Jewish Exodus to Palestine mandate, for example. Ships sailed to Palestine, beached, hoping their passengers could disappear before authorities appeared.
The ship will be impounded and the captain will be arrested and prosecuted. That means that the ship won't be going anywhere, until steep fines are paid. What the organizers of those trips did was find very old ships that could be ditched commanded by captains who could be bribed.
The situation in Palestine (before it became Israel) was a bit different from the situation in your question. British mandate authorities were at a loss what to do. Pre-war Canadian and American authorities were not.
In your example there wouldn't be any doubt. Supposing a captain brings his passengers ashore in a remote desolate area, he will be arrested in the next port of call, and his ship will be impounded. At least he can expect to be charged with illegal immigration. He probably would be charged with premeditated manslaughter or murder, the crew would be complicit. When you bring a lot of people ashore in a remote area, people run the risk of dying there. They don't actually have to die, running the risk is enough to make the charges stick.
I used to work in a travel agency as cruise expert. What I described are international laws at sea: SOLAS. The International Convention for the Safety of Life at Sea regulations are international, they apply to all maritime nations. Of course they didn't exist before 1974, but local laws and international treaties did exist and were internationally enforced.