How was Pacific mapped?

The Pacific was mapped through a combination of early explorations by European navigators, such as Ferdinand Magellan in the 16th century, and subsequent voyages by explorers like Captain James Cook in the 18th century. Advances in navigational tools, such as the sextant and chronometer, allowed for more accurate mapping of the ocean's vast expanse. Additionally, modern techniques, including satellite imagery and sonar, have further refined our understanding of the Pacific's topography and features. These efforts collectively contributed to the detailed maps we have today.