Alex,
While I have no advice for you in joining the Dutch Marines, I have some experience with the Dutch Navy. While I was in the US Navy, we did some ops with a Dutch ship prior to both of us pulling into Den Helder (a beautiful city BTW). I was amazed at the cleanliness of Dutch ships and the way they handle duty on the ship. After normal working hours, they left 1 person onboard and pulled up the brow after everyone else went home.
In the US Navy, there is somewhere between 1/3 and 1/4 of the ships crew onboard at any given time. Every 3rd or 4th day was spent on the ship even when it was in port. I'm thinking that if I were Dutch, I may have made a career out of the Navy.
Good Luck and let us know what you decide!
-Fred