I do not know if this true. If true I am looking for scientific explanations....................
"Temple of lord Murugan at Tiruchendur which is very close to the sea shore. Tiruchendur Lord Murugan Temple is on the sea shore - within 100 metres of the waves. The Temple is a cave with the entrance at the sea level and the cave inside is sliding down to the Sanctum Sanctorum of the Lord Subramaniam ( Murugan ) . When we stand in front of the deity, the sea
water level outside is higher than our heads. There is every likely hood that tidal waves and tsunamis can rush in and fill the cave Temple with sea water. In the history of the Temple, it is mentioned that the Water God (Lord Varuna) has promised Lord Murugan that he will not cross the boundary of the Temple.
It seems the Water God has kept his promise. While the tsunami on 26/12/04 has lashed the eastern coast of India and inundated all places near the coast deeply, the sea water did not enter the Temple. At 10.00 Hrs on the fated day ( 26/12/04), the sea near the temple receded by a Kilometre - people could see there a big crater with rocks visible - gradually the sea came back to its original level. But sea water has entered Jeeva Nagar located opposite Tiruchendur Bus stand at 12.30 Hrs.
All other coastal areas near Tiruchendur were affected by the lashing of tsunami. The Temple area is unaffected as the sea receded there as though to keep the promise given."