Minorca's coastline with has hundreds of bays and inlets and a number of small islands that makes it perfect for exploring by kayak or stand-up paddleboard (SUP). Mornings and evenings are the best times when the winds are generally lighter and there is less boat traffic. The water quality around the coastline (especially once outside the busier or more enclosed bays) is very good and visibility is excellent even at considerable depths. Expect to see fish, maybe octopus, and probably some jellyfish too.
Kayaking is popular on the island and open-top kayaks can easily be hired. Paddleboarding is relatively unknown.