Why did European traders begin to travel to Asia by sea?

Answer 1

There are many reasons for that decision taken by the traders.

1. In general transporting will be cheap if you take the route via sea than the land. (Ref: An inquiry into the Wealth of Nations by Adam Smith)

2. before European traders discovered the sea route to Asia, they use to take the land route, which passes via the Middle East. And when once the sea routes were discovered the costs of many imported goods fell to one third of its value.

So the European traders started to travel to Asia by the sea.

Answer 2

So they can movie supplies easier.