Paumotu Group (Tuamotu Archipelago, French Polynesia)
The remaining four ships left Callao on 13 July, finally beginning their primary mission of charting and describing the little-known islands of the Pacific. Remaining below the equator, their first destination was the Paumotu Group (Tuamotu Archipelago, French Polynesia). On 13 August, just five days short of the one year anniversary of their Norfolk departure, they arrived at Clermont de Tonnere Island (Reao Island). The next day the squadron began surveying the island, triangulating between pairs of ships and fixed points on shore. They calculated distances by having the primary ship fire a cannon and the secondary crews noted the time between seeing the flash and hearing the sound. The following day a party went ashore to collect specimens and to try to communicate with the islanders. The latter effort failed. The islanders tried to drive the strangers off by brandishing spears and clubs and hurling stones. Finally feeling the need to show force, Wilkes sent them fleeing by having his men fire mustard seed shot at them. They later learned that hostility shown was due to the islanders having been fired on by pearl fishermen in the past.
Over the next month the ships surveyed sixteen islands. Because of his fear of the hostility of the islanders, Wilkes only occasionally allowed scientifics to go ashore, a restriction that quickly resulted in their discontent. One day Lt. Hudson of Peacock allowed the scientists on his ship to land and after their return in the evening Wilkes sent a Hudson a severe note. Afterwards such trips were more tightly controlled. Wilkes always considered the scientific mission secondary to the military mission of surveying and acquiring astronomical data. After weeks of notations in his log about islands being surveyed but few opportunities for naturalists to go ashore, Titian Ramsay Peale exclaimed in his diary in large letters, "What was a scientific corps sent for?" The next day they reached Raraka Atoll and were allowed ashore to explore it on that and the following day. There they met about 40 peaceful islanders, who had native-born missionary among them. Their chief was missing his left hand, it having been bitten off by a shark. At Honden Island (Pukapuka) Wilkes made a careful study of the structure of the coral island. He commented that such an island may seem beautiful from a distance, but landing on one revealed only sparse and stunted vegetation.