I do know about Kolyma, which was basically a gulag for political and religious dissidents in Siberia. I was thinking about it because of the ship you mentioned.
A special fleet of slave ships was organized in Vladivostok, and carried hundreds of thousands to their fates. The vessels of the fleet were fitted out to enable the maximum load of prisoners in the minimum space. A typical slave ship was the Dhzurma. Erected around the walls of its cargo holds were wooden structures of tiered bunks, four high, while the floor served as the fifth. Each of the bunks accommodated five men in lying position. Prisoners had to slide in feet first with their heads facing the passages to avoid suffocation. If even these cramped places were lacking, men had to lay in the passage-ways, and these one-way voyages would last six to eleven days.
Sanitary arrangements on board consisted of two 50-gallon barrels called parashi, which were emptied into the sea. In bad weather, the barrels would spill, adding to the already thick stench below decks. An outside latrine was also available, but only accommodated a few prisoners at a time, and the lines were always long. Barbed wire surrounded the outside latrine to prevent prisoners from jumping into the sea.
Here you go - the thread isn't all that long. I don't remember the ship's name offhand, I'll probably have to go back to the book or some history volume. Or it may be on the net. We'll see.
Anyway, I see LL's little spin about Jews escaping to South America comes before his take on the sending-back thing.