This is the famous "Ocean" Etude in C minor by Frederic Chopin. It's a very stormy piece that starts out in the key of C minor but then becomes Major in the key of C Major. There are many modulations to different keys in this piece. It's one of Chopin's most famous pieces. 

The "Ocean" Etude in C minor by Frederic Chopin

Bryan Eyberg is a classical pianist who specializes in the music of great composers such as Frederic Chopin and Sergei Rachmaninoff. He is also a fan of composers like J.S. Bach, which you can hear here on his Sound Cloud profile. Bryan has been playing the piano since the age of seven.