hi debra
Have just joined and seen your post re your dad. did you get the cruise booked??
My first thought was holiday insurance. Both me and my sister have had cancer and it can be a bit tricky and expensive to get. It all depends on how the individual feels. Rad therapy can certainly take its toll. and being in the middle of the ocean might not be the best idea, from the point of view of seeking medicsl attention if needed.
just a thought
best wishes to you
becks.