Surfing on Sine Waves is a studio album by the musician and producer Richard D. James under the alias Polygon Window. James is better known as Aphex Twin. The record was released on 11 January 1993 through the label Warp. It entered the UK Dance Albums Chart at No.2 on 23January 1993. James' previous album, Selected Ambient Works85–92, was then at No. 9 on the chart, and James briefly had two records in the Dance Albums Top 10 under different pseudonyms. The 2001 reissue edition includes the previously unreleased tracks "Portreath Harbour" and "Redruth School".
The cover of the album features a photograph of Chapel Porth beach in Cornwall, where James spent time with his sisters as a child; James thanks the seaside village in the liner notes. The title Surfing on Sine Waves was chosen by Warp founder Rob Mitchell after James mentioned that "loads of people I knew growing up in Cornwall were poser surfers and I didn't wanna hang around with them." The record is the second release in Warp's Artificial Intelligence series.
Ned Raggett of AllMusic praised Surfing on Sine Waves as "a great collection of abstract electronic/dance madness, caught somewhere between the driftiness of his more ambient works at the time and the rave-minded nuttiness of 'Digeridoo.'" Mark Richard-San of Pitchfork wrote, "Catchy, melodic and memorable tracks are what made the Aphex Twin so wonderful at his best; Surfing on Sine Waves has a handful of these, albeit in rough, embryonic form."
In 2012, Fact placed Surfing on Sine Waves at number 26 on its list of the "100 Best Albums of the 1990s". In 2017, Pitchfork placed it at number 26 on its list of the "50 Best IDM Albums of All Time". Writing for Pitchfork, Andrew Nosnitsky said, "These days, Surfing doesn't get mentioned as often as the louder, more ambitious, 'proper' Aphex records that would follow, but it's easily as refined on a technical level—and maybe even more emotionally rewarding."