Some explorers got the fame, glory and other grand things. Christopher Columbus got his own day, Marco Polo got a game named after him. Here are some explorers as important with less or no fame at all.
Pytheas, he was a Greek sailor, navigator. He lived in Marseilles, he was a great navigators of the sea like other Greeks of the time. He traveled to Cornwall and even got up to the British Isles. He even reached Norway, which he called Ultima Thule. Some historians believe he also landed on Iceland. He had a book in which he wrote all of his travels but it got lost. But not to worry, Polybius, a writer of the time, he rewrote all of his ventures.
Abdullah Muhammad Ibn Battuta, he traveled more distance then any other traveler of that time. Around 75,000 miles no other travelers would overcome that until the invention of steam. He was born in a small place, Tangier, in North Africa. He went to Egypt and visited most of the Muslim world. He went as far as China, Sumatra, Georgia and also Granada. He also wrote a book in which he told the tales of the times he meet 50 different kings, including the dreaded Tughluq of India.
Cheng Ho, in the end of the Ming Dynasty, when the last Mongol fort was destroyed in China. The Ming soldiers captured a few Mongol boys, they castrated them and put them in the service of the kings. One of them was very grateful of the king. In 1400s, he visited Mozambique, Arabia, Egypt. Many believe he traveled the world even before Magellan.