A. Relationship Cruises: 

• Family, Siblings, or Friends-Only: to re-new old intimacies, heal old wounds & share new stories.
• Adults only: avoid family/kid mayhem by enjoying “adults-only” stuff.
• Wedding: I am a bachelor, so, haven’t a clue.?� 
• All-women / All-men: Girlie things vs guy stuff.    NOTE: These are NOT the European style “I’m free!” raucous bachelorettes or bachelor bacchanals which many hostels outlaw.

    B. Sports Cruises: Any sport imaginable from medium fitness to high intensity either on-board ship or off.
    (1) Onboard ship:
         Snorkeling and Scuba Diving: if stops at
             coral reefs or marine parks, often with
             certification courses.
         Rock Climbing: onboard climbing walls.

                                        Ok! Ok! I know he has 4
                                        arms or do they each
                                        have 3?       IDK, but AI
                                        is still learning. LOL
         Extreme Sports: paragliding, bungee jumps, or extreme water
              sports
         Ice Skating: on some ships: Royal Caribbean's Oasis-class                        
              ships.
         Mini Golf: with scenic or themed courses.

    (2) Onboard ship or in-port: often varies with ship size 
         Jet Skiing/Wave Runners/ sailing/windsurfing: ship’s marine platform
         Zip-lining: some ships: Royal Caribbean's zip-line from ship's mast.
         Marathons or Runs: Some cruises organize runs or even marathons.
         Basketball, Volleyball, Soccer:
         Golf: golf simulators onboard.

  (3) In-port:
         Kayaking & Paddleboarding: at scenic
             or wildlife-rich locations.
         ATVs & Mountain Biking: if terrain
            allows, Shore Excursions.
         Gym, Fitness & Training Classes:
            well-equipped, yoga, spinning,
            or boot camps: at varying fitness levels.
         Golf:  arrange tee times at ports. 

     C. Expedition Cruises: tailored for explorers, visiting remote or ecologically significant areas: Galápagos, or Antarctica, etc. with education components.
         Survival Skills: survival techniques demos & classes: basic first           ➩➩➩➩➩
              aid to wilderness navigation.

    D. Activity Specialty: Hobbies & Interests: art & architecture, cooking, music, history, science, birding.          Artisans of Leisure:
           https://www.artisansofleisure.com/Cruise/Arts_tours_luxury_travel.html),

    E. Eco & sustainability: range from ESG, environmentally focused activities to Nat’l Geo~ Cruises  & Rick Steves’. 

    F. Luxury Boutique: Silversea Line’s small ship’s all-inclusive luxury: personal service, exclusivity, & high-end amenities focus. 

   G. Special Occasion Cruises: Christmas, New Year’s etc.

   H. Educational & Cultural Cruises: Often in partnership with universities. museums, theaters, libraries, art galleries, National Geographic, Cultural Centers: (British Council), Music & Dance Companies: (Royal Ballet), Film Institutes (Sundance Institute), Cultural Heritage Sites: (UNESCO  Sites), Conservation Societies.

     I. Volunteering: Some Cruise operators promote volunteer
experiences & pro-active sustainability travel (eco lodgings, etc) all over the world. Some Volunteer opportunities are for a few days or weeks to months. Curiously, some often charge a weekly fee; $180 > 3000/week or you work for basics: food, tools, experiences. Huh? 

              International Volunteer HQ (IVHQ:                       
        https://www.volunteerhq.org/destinations/

  J. Specialty or Narrow Focus: Religious, Shopping, Gastronomic (food), Genealogy, Christmas Markets Getting-Back-To-Your-Roots.
        1) Trafalgra Cruises: Japan’s “Cherry Blossoms” Cruises,
        2) Vivator: Top Europe Ghost Cruises:
   https://www.viator.com/Europe-Cruises/Ghost-&-Vampire-Cruises/d6-g4-c118 

    K. Curious, esoteric, contrived, silly Trips:
        1) Single, Yet Ready-To-Mingle Trip:      Huh?
        2) Do-Nothing-At-All Trip: go to Motel 6 & watch TV; save money & hassle

    L. Themed Cruises: Total theme immersion:   
         Music Cruises: rock, country, decades
             (80s or 90s); live shows, themed parties, with
             celebrity meet-&-greets.
         Pop Culture Cruises: Star Trek to
               Harry Potter, etc with activities, talks, &
               stars/creators meet-ups 
         Culinary & Wine Cruises: celebrity chefs, wine
               tastings, & exclusive dining’s special menus
         Fitness & Wellness: yoga retreats, wellness seminars, or
               spa-focused.
         Holidays, etc: Christmas, New Year's, Super Bowl:  etc.