does anyone know who the first European explorer was to travel to the Pacific Ocean?

Captain Cook?

Magellen

Probably Ferdinand Magellon because he was the first to circumnavigate the globe. This trip took place from 1519-1522. The Strait of Magellan is named after him.

Cabrillo He crossed Panama on foot to see the Pacific and gave it it's name.

I'll guess it was the Danish capt. Bering (Bering Sea) under the tsarist flag. ???????????????????? You didn't say from the east or west, oh Marcho Polo maybe?

Some portuguese sailor. They reached Moluccas (Indonesia) some years before Magellan crossed the Magellan Strait into the Pacific.

Probably the Venetian traveller and writer, Marco Polo. He joined his father (Niccolo) and uncle (Maffeo), who had travelled to China as merchants (1260 - 69), when they began a journey overland back to China (1271). Once there, he learned Mongolian and served the emperor Kubla Khan until he returned to Europe "BY SEA" 1292 - 95.