Sverige

Sjöormen class (Type A-12) SSK: 5

Sor Sjöormen	Kockums, Malmö	-65	25-1-67	31-7-67	to Singapore
Sle Sjölejonet	Kockums, Malmö	-66	29-6-67	16-12-68	to Singapore
Shu Sjöhunden	Kockums, Malmö	-66	21-3-68	25-6-68	to Singapore
Sbj Sjöbjörnen	Karlskrona	-67	6-8-68	28-2-69	to Singapore
Sha Sjöhästen	Karlskrona	-66	9-1-68	15-9-69	-

Singapore: 4

Challenger	Karlskrona	-67	6-8-68	28-2-69	ex Sjöbjörnen; lev. 97
Conqueror	Kockums, Malmö	-66	29-6-67	16-12-68	to Singapore; lev. 99
Centurion	Kockums, Malmö	-66	21-3-68	25-6-68	to Singapore; lev. 99
Chieftain	Karlskrona	-67	6-8-68	-	to Singapore; lev 2001

In 1995, Singapore purchased 4 A-11 Challenger Class (ex-Sjöbjörnen Class), the first of which was launched in 1968. The Challenger Class were not only refitted for tropical conditions, but also received weapons system and sensor upgrades. These  submarines  performed very well in exercises against US Navy and Royal Australian Navy units, proving that these old boats, when handled well in littoral conditions, are quiet and maneuverable subs that are able to give a pretty good account of themselves.