How do you go about getting a job on a cargo ship? I mean a big, international freight ship. Obviously you'd have to have your passport in order, but would you need visas? Would they run security clearances? That could be a problem...

http://www.careers-at-sea.org/Links/links.htm

Good luck.

Dont do it if your intention is to see the world while at work. You won't. You'll see a lot of water and you'll be in port for half a day to two days maximum on a modern merchant ship, and during that time you'll be at work. You'll be lucky if you can get a couple hours off the ship. Mostly you'll see a lot of airports and water. But it is a great life if you're up for it. I know this from a friend of mine who is studying to be a merchant marine deck officer.

Also, if you don't have any training and experience you could have a hard time finding a job. The untrained ratings nowadays are almost all people from third world countrys because they're cheaper. If you have the skills to work on a tanker or in off-shore, you'll have no problem at all to find a job.

Other than that, get to a city with a big port and look for a job. You employer will tell you what administration you have to take care off yourself. Just make sure you have a passport which is valid for a couple years when applying for a job, you always have to take care of that yourself and it can take some time. Security checks might be a problem you say? If you're talking about drug tests, make sure you're clean. No drugs on board. More and more companies even forbid alcohol on board. If you're a wanted criminal, don't even think for a moment getting a job on a ship will get you out of the country. It won't. You'll have to pass customs just like everybody else leaving and entering the country.