Why was sea travel so dangerous during the age of exploration?

Answer 1

For many if not most it was the lure of discovering gold and / or finding the source (and getting to control the trade) of rare and very valuable spices. The seas were important to discover and chart as being the new trade routes: only shipping could provide bulk transport to the motherland of those commodities.

For a few, it was pure curiosity. Certainly the early Portuguese discoverers already knew that the world was round and also had a fairly good idea of its size. But even in the early stages, the finding of trading opportunities was always behind the travels.

Answer 2

they usually wanted some more money, wanted to get away from their lives at home or to prove something of themselves

Answer 3

They wanted gold and riches.