The Chinese deep-sea explorer ship, Zhang Jian, has set sail from Shanghai to the New Britain Trench in Papua New Guinea.
The state-run news agency, Xinhua, says scientists aboard the ship will study the terrain, water and sediment in the 8,000 metre-deep trench, which is believed to be rich in resources.
The ship's departure follows the visit of Papua New Guinea's prime minister, Peter O'Neill, to China last weekend, where he signed agreements for direct flights and to encourage investment.
Also on Sunday, Peter O'Neill announced that his country supported China's claim to most of the disputed South China Sea.
The announcement came days before an international tribunal ruled there was no legal basis for China's claims, which clash with those of several other southeast Asian countries.
Mr O'Neill's statement highlighted a change in position for PNG, as his foreign minister, Rimbink Pato, last month told RNZ International that PNG supported the international tribunal.