Final answer:
Celtic monks took to the sea and built monasteries in remote places like islands and caves in Iceland for isolation and protection.
Step-by-step explanation:
Celtic monks often took to the sea and built their monasteries in remote places like craggy islands and caves in Iceland for several reasons.
Firstly, these remote locations provided isolation and solitude, which were essential for the monks to lead a contemplative and ascetic life.
Secondly, the harsh environments of these places made them less appealing to Viking raiders, who often targeted monasteries for their loot. By choosing remote and hard-to-reach locations, Celtic monks could protect their religious artifacts and manuscripts.