Records show that he visited Guangdong (China) and Patagonia (South America) on whaling expeditions, and that he became captain of a ship in 1832.

[3] On November 9, 1843, Cooper left Sag Harbor as captain of the 440-ton ship Manhattan on a whaling voyage.

[4] It was about the first of April 1845 when Captain Cooper passed by the neighborhood of St. Peters (a small island lying a few degrees to the S. E of Japan) to the northern ocean for whaling.

When Captain Cooper was exploring the shore to hunt turtles, he met 11 Japanese sailors on the coast who had been shipwrecked on St. Peters many months ago.

Captain Mercator Cooper decided to take them to Jeddo, although there was a clear rule published by Japanese court prohibiting foreigners from going to Japan.

After Captain Cooper left St. Peters and sailed a day or two en route to Japan, he found a wrecked vessel on the ocean.

Outside Edo Bay four of the survivors took a Japanese boat with a message that Cooper wanted to deliver the remainder to the harbor.

[6] The Japanese normally wanted to avoid contact with outsiders due to the Tokugawa shogunate's official policy of national isolation.

In August 1851, Cooper again left Sag Harbor, this time as captain of the 382-ton ship Levant[b] on a mixed whaling and sealing voyage.

The next morning, the ice shelf still in sight, with high mountains looming behind it, he sailed the ship close inshore and ordered a boat to be lowered.