Oh crap! Do i *really* need invitations?!!?

Yes, I would say that if you are inviting people to your wedding, especially getting married on a cruise ship, people should have their paper invites so that they have pertinent information about your special day!!

I don't think it's necessary for how you're doing it since it sounds like you already got a verbal yes from people considering you had to book all the cabins 2 years ago, but I would at the very least do an electronic invitation that you can post in the Facebook group or send to everyone's emails and then have them RSVP online. This way there is no confusion on either end of who is invited and who is attending and you don't have to pay for invitations/stamps/return stamps. You know your guests best and not everyone will care about not getting a paper invite that they're just going to throw away anyways.

For a cruise wedding. There is a long-standing exception for a wedding or formal event coming up in 2-3 weeks, to just make a phone call. But with all your planning time, NO. Issue invitations . I suggest you get the most basic engraved printed invitation, the info plus a nice embossed border, with 1 envelope and no add-ons. Go to a local print shop of the old time variety. They will show you cards of the most basic, classically the standard formal invitation, for far less than any online option. We did. And it was nice to look in their sample book, choose, and get them 2 days later. And under the weight for a first class stamp, no extra postage. Classy embossed and engraved stationery used for formal parties and such, and old style printing, do not have the custom colors, trademark designs many use for less than formal weddings, and they do not have the ridiculous mark up of everything wedding.

I think you can never go wrong with physical invitations! They don't need to be fancy

Yes people get paper invitations.

For what your doing, I don’t think that you need to send invitations.

If you're keeping in touch with everyone I don't think that it's really important! If it would make you feel better then go for it but I wouldn't "require" one.

If it were me, I'd still send them.