HM03 Surf Guide - Pokemon Fire Red & Leaf Green
HM03 Surf is found inside of the Safari Zone, a location that's found just off of Fuchsia City. If you make it through the Safari Zone to the far southwestern side before time runs out, speak to the attendant (shown in the screen shot above) to be given HM03 Surf. A picture of the building that he's located in is shown in my screen shot below.
In addition to finding HM03 in the Safari Zone, you'll also find HM04 Strength inside of the Safari Zone. This one is obtained by picking up the Gold Teeth in the Safari Zone and handing them to the warden located in Fuschia City. More info on that in the HM04 Strength Guide.