Wiktionary
vb. (context idiomatic English) To barely begin; to see or do only a fraction of what is possible.
Wikipedia
Scratch the Surface is Sick of It All's third (official) studio album, released in 1994. It was the band's first major label recording on Eastwest Records, their first venture away from an indie label.
Although the album did not reach any of the major charts, Scratch the Surface subsequently became Sick of It All's most successful release, and it produced two singles "Scratch the Surface" and "Step Down". The video of "Step Down" was also featured in the Beavis and Butt-head episode "Premature Evacuation".
Usage examples of "scratch the surface".
Orr had mostly just talked, generally about what he had seen and heard over the past millennia - and over fifteen years he had barely managed to scratch the surface of his experiences.
It would take a hundred times what they proposed even to scratch the surface of this problem.
A few minutes in a tub would hardly suffice to scratch the surface.
Nobody was doing more than scratch the surface of the work that was offering, and over and above the lot of it there were things like the transport of pilgrims to Jiddah and transport of food to relieve the perennial famines in the Hadramaut.
The Chereks didn't really need too much encouragement, Since if you scratch the surface of any normal Cherek, you'll find a Pirate lurking underneath.