Hi Phil: What happens with guns depends on the present policy, the type of gun(s) and the security which you can provide for it onboard. Most jurisdictions have a tougher policy towards hand guns than toward shotguns or rifles. A proper, lockable storage for weapons and ammunition also helps. As far as the Marquesas islands specifically, I cannot tell you what the policy is today. It used to be the Maruesan gendarmes ignored the issue and let the folks in Papeete deal with it. Steve