Hi there! As you know, we were on the same cruise as you. While I generally agree with you about ships excursions, we had two great excursions on that cruise. The first was in Salvador de Bahia where we did a drumming workshop. It was great - there were only 4 of us on it. It included a short walking tour of the old town with a guide who was a local and knew her stuff, then the workshop which was great fun, then a snack & drink in a lovely little restaurant.
The second was a drive around La Palma. We stopped at two little towns & had time to look around and on the way back we drove along a road right next to the volcano ash field, which was amazing - on one side of the road the houses were fine, on the other side many were partially buried. Fascinating, and tragic - our bus driver had lost his house along with many other residents.
We had also booked a ‘glass bottom catamaran’ tour which may be one of the ones you mentioned - we heard everyone had been refunded! Although it was on the first day, we were able to cancel because it was not going to be in a glass bottomed boat, as advertised.