The French captured her in the Indian Ocean in 1804 and then kept her at Île de France where she served as a prison ship.

[6] On 17 April the French frigates Belle Poule and Atalante captured Althea in the Indian Ocean (7°0′S 92°30′E / 7.000°S 92.500°E / -7.000; 92.500).

One problem Miller faced was that the frigates were firing their long 18-pounder guns from a range that Althea's carronades could not reach.

In March 1806, Captain William Richardson, in Althea, took on water at Pulo Timoan, and also took a number of navigational bearings.

[11] Between August and October 1807, privateers and French naval vessels from Mauritius captured Althea, Gilwell, Elizabeth, Trafalgar, Mangles, Susanna, Caroline, Succedany, Maria, Eliza, Udny, Highland Chief, Resource, Louisa, and Mersosa.

[12] Lloyd's List reported on 16 April 1808 that the country ships Eliza, Resources, Gilwell, Loi'a, and Althea had been taken in the Bay of Bengal.

[13] On 1 November 1807 at Port Napoleon, Richardson, C. Bean, late master of Gilwell, R. Dickie, late master of Elizabeth, and some others wrote a letter to Léonard Motard, captain of Sémillante, for his kind and courteous treatment of them while they were his prisoners.