Question:
Are me and my wife (niddah) allowed to ride a boat together?
Does the boat size make a difference?
If there’s someone else on the boat? (ex. Gondola ride in Venice)
Answer:
If it is a big boat, that her movements are not going to move the boat, then it is permitted, however in a small boat, if you are going for a pleasure ride then it isn’t permitted. Id there is someone else in the boat then it is permitted.
Best wishes
Sources:
Rema Y:D 195-5