How exciting to embark on your first cruise! Black trainers can totally work for smart casual on board, especially if they're clean and in good condition. I remember when I packed my trusty Nike shoes for a cruise; they were perfect for exploring the ship and lounging in comfort. If you're unsure, a quick shoe shopping trip in Southampton could be fun—maybe find a versatile pair that suits both day and evening wear. Boat decks can be slippery, so shoes with good grip are a must! Most importantly, enjoy your cruise and all the new experiences ahead.