Thousands of people on the Indonesian island of Bali have taken part in an evacuation drill to mark the second anniversary of the Asian tsunami.
The drill used real-time warnings relayed from Jakarta
The drill was aimed at raising awareness and testing new technology.
Elsewhere Sri Lanka declared a national safety day while survivors and mourners across the region lit candles, visited graves and held moments of silence.
A magnitude 9.0 quake triggered the Asian tsunami on 26 December 2004, claiming almost 250,000 lives.
Almost 170,000 died in Aceh in Indonesia with thousands more killed in Thailand, India and Sri Lanka.
The drill on Bali involved several thousand people. A concert was organised to draw people, followed by a mock quake and the sounding of tsunami sirens.
The exercise involved real-time warnings sent from Jakarta to radios on the beach.
However, the BBC's Lucy Williamson in Jakarta says a full warning system is far from complete.
Sirens along coasts in Aceh, Bali and West Sumatra are only partially finished, she says, and the framework for a national warning system with detection devices on land and sea is not ready either.
The government coordinator for the early warning system says delays were due to problems with funding that have only recently been resolved.
In Aceh, mourners visited mosques and mass graves to mark the day.
The International Federation of the Red Cross says many villages there remain vulnerable to disaster.
Spokesman John Sparrow said there was "very little barrier between the communities and the sea so even without a tsunami, high tides are coming into the rice fields, destroying the rice fields".
In southern Thailand, survivors and mourners gathered to throw flowers out to sea in memory of the 5,400 victims there, half of them tourists.
Ceremonies were held across southern Thailand
Buddhist monks said prayers and candles were lit on beaches in ceremonies along the Andaman coast.
A cemetery was also opened for the hundreds of unidentified victims.
Sri Lanka declared a national safety day, with events to create awareness on dealing with future emergencies.
President Mahinda Rajapakse was to unveil a giant Buddha at Peraliya, where up to 1,000 people were thought to have been killed when tsunami waves struck a train - the world's worst rail disaster.
Vehicles across the country halted at the time the waves struck, at 0925 (0355GMT), to mark a two-minute silence.
Sri Lanka also erected the first of 100 coastal warning towers - at Hikkaduwa.
Outgoing UN secretary general Kofi Annan made a plea on Tuesday for the devastation of the tsunami not to be compounded by a return to civil war in Sri Lanka.
Other memorials were held across the region, including in India and Malaysia, although many were more low-key than last year.