This is a great question. Let me give you a few reasons, but let me start with a little historical context.
It is important to set the dates for the age of exploration. Most people would agree that the age of exploration started in the 15th century and lasted until the 17th century. There were several reason for this new desire for exploration (other than the innate desire of human to explore).
First, exploration was based on needs. When the Ottoman Turks took over Constantinople, new routes were needed for the spice and silk trades. Hence, people were looking for alternate routes. Needs and desire for money are great motivators.
Second, with the growth of nationalism, nations were in competition to beat others in the race to acquire lands and commodities, such as silver and gold. Competition, therefore, was another great reason for the growth of exploration.
Third, with the renaissance, there was a mental shift in worldview. There was a feeling that there was a surpassing of the past. There was a new confidence that people could excel the ancients. This led to daring on the seas.
Finally, of course, with more people sailing, there was more knowledge and greater growth in nautical technology.