Pirates attacked 41 vessels in the first three months of 2007, down sharply from the same period a year earlier, a global watchdog has said.
Indonesian waters are notorious for pirate attacks
The International Maritime Bureau said the number of attacks between January and March was the lowest since 1998.
It said improved vigilance and security measures had helped reduce them.
Indonesian waters remain the most dangerous for seafarers, with nine attacks. Nigeria comes close behind, with attacks climbing from four to six.
"Although it continues to top the table, Indonesia should be applauded for the proactive efforts it has taken to tackle the problem," said the International Maritime Bureau (IMB).
Indonesia's decision to bolster the number of sea patrols in its notoriously risky waters resulted in the number of attacks halving since the first quarter of 2006.
But the IMB said it was worried by the increasing number of attacks off the coast of Africa.
Referring to Nigeria, the IMB said: "These have included a number of violent attacks against vessels and crew working in offshore oil installations where crews have been assaulted and abducted."
The body also recommended that ships sail at least 75 nautical miles from the Somali coast, where it said attacks continued in "a worrying trend".