This is a blowing of "Titanic"'s triple- toned steam whistles, the largest ever built.
"Titanic"'s bronze whistles were last sounded on a routine check on the noon of April 14, 1912.
Being two feet high with a weight of 750 pound, operating whistles were only attached to the two forward funnels. The other two funnels had mockups for looks only.
The whistles were recovered from the bottom on an expedition in 1993 and blown again on February 21, 1999, with less pressure than in 1912 (then, 215 psi) for fear of damaging them. However, their pitch would only be higher had they been blown with the original pressure.