On the 20th of January, 1825, the Espérance at last rejoined the frigate; and, two days later, two envoys arrived from the court at Hué, with orders to ask Bougainville for the letter of which he was the bearer. But, as the latter had received orders to deliver it to the Emperor in person, this request involved a long series of puerile negotiations. The formalities by which the Cochin-Chinese envoys were, so to speak, hemmed in, reminded Bougainville of the anecdote of the envoy and the governor of Java, who, rivalling each other in their gravity and diplomatic prudence, remained together for twenty-four hours without exchanging a word. The commander was not the man to endure such trial of patience as this, but he could not obtain the necessary authorization of his explorations, and the negotiations ended in an exchange of presents, securing nothing in fact but an assurance from the Emperor that he would receive with pleasure a visit of the French vessels to his ports, if their captain and officers would conform to the laws of the Empire. Since 1817 the French had been pretty well the only people who had done any satisfactory business with the people of Cochin-China, a state of things resulting from the presence of French residents at the court of Hué, on whom alone of course depended the maintenance of the exceptionally cordial relations so long established between them and the government to which they were accredited.

The two ships left Touron Bay on the 17th February for the Anambas Archipelago, which had not as yet been explored; and, on the 3rd of March, they came in sight of it, and found it to bear no resemblance whatever to the islands of the same name, marked upon the English map of the China Sea. Bougainville was agreeably surprised to see a large number of islands and islets, the bays, &c., of which were sure to afford excellent anchorage during the monsoons. The explorers penetrated to the very heart of the archipelago, and made a hydrographic survey of it. Whilst the small boats were engaged upon this task, two prettily built canoes approached, from one of which a man of about fifty came on board the Thetis, whose breast was seamed with scars, and from whose right-hand two fingers were missing. The sight of the rows of guns and ammunition, however, so terrified him that he beat a hasty retreat to his canoe, though he had already got as far as the orlop-deck. Next day two more canoes approached, manned by fierce-looking Malays, bringing bananas, cocoa-nuts, and pineapples, which they bartered for biscuits, a handkerchief, and two small axes. Several other interviews took place with islanders, armed with the kriss, and short two-edged iron pikes, who were very evidently pirates by profession.

Although the French explored but a part of the Anamba group, the information they collected was extremely interesting on account of its novelty. The first requisite of a large population is plenty of fresh water, and there is apparently very little of it in the Anambas. Moreover, the cultivable soil is not very deep, and the mountains are separated by narrow ravines, not by plains, so that agriculture is all but out of the question. Even the native trees, with the exception of the cocoa-palm, are very stunted. The population was estimated by a native at not more than 2000, but Bougainville thought even that too high a figure. The fortunate position of the Anambas—they are passed by all vessels trading with China, whichever route may be taken—long since brought them to the notice of navigators; and we must attribute to their lack of resources the neglect to which they have been abandoned. The small amount of cordiality and confidence met with by Bougainville from the inhabitants, the high price of provisions, and the destructive nature of the monsoons in the Sunda waters, determined him to cut short his survey and to make with all speed for Java, where his instructions compelled him to touch. The 8th of March was fixed for the departure of the two vessels, which sighted Victory, Barren, Saddle, and Camel Islands, passed through the Gasper Straits—the passage of which did not occupy more than two hours, although it often takes several days with an unfavourable wind—and cast anchor at Surabaya, where the explorers were met with the news of the death of Louis XVIII. and the accession of Charles X. As the cholera, which had claimed 300,000 victims in Java in 1822, was still raging, Bougainville took the precaution of keeping his crew on board under shelter from the sun, and expressly forbade any intercourse with vessels laden with fruit, the use of which is so dangerous to Europeans, especially during the rainy season then setting in. In spite of these wise orders, however, dysentery attacked the crew of the Thetis, and too many fell victims to it.

The town of Surabaya is situated one league from the mouth of the river, and it can only be reached by towing up the stream. Its approaches are lively, and everything bears witness to the presence of an active commercial population. An expedition to the island of Celebes having exhausted the resources of the government and the magazines being empty, Bougainville had to deal direct with the Chinese merchants, who are the most bare-faced robbers on the face of the globe, and now resorted to all manner of cunning and knavery to get the better of their visitors. The stay at Surabaya, therefore, left a very disagreeable impression on all. It was quite different, however, with regard to the reception met with from the chief personages of the colony, for there was every reason to be satisfied with the conduct of all connected with the government.