Hay-a-Park Gravel Pit is a Site of Special Scientific Interest, or SSSI, adjacent to the east side of the town of Knaresborough, North Yorkshire, England.

Having been a disused and flooded quarry since the 1970s, it now consists of the large Hay-a-Park Lake and three smaller ponds, besides associated reedbeds, scrub, woodland and grassland.

[3] Edward's fifteen-year-old wife Philippa of Hainault was given this land on the occasion of her marriage; she was later the mother of the Black Prince (whose statue stands in Leeds City Square) and John of Gaunt.

[4][nb 1] Another story says that in the 11th or 12th century Henry I conferred the lands to Gamel de Scriven, and they remained in the family under various names including Edward II until the last heir, Sir Charles Slingsby, died falling from his horse into the river in 1869, leaving no issue.

"[1] Hay-a-Park Gravel Pit is a 44.8687 hectares (0.4487 km2; 0.1732 sq mi) biological Site of Special Scientific Interest (SSSI),[9] consisting of "standing open water and canals.

"[1] It is one of about eight SSSIs in the Harrogate region,[12] others being Ripon Parks,[13] Farnham Mires,[14] Hack Fall Wood,[15] Brimham Rocks,[16] Cow Myers,[17] Kirk Deighton[18] Mar Field Fen,[19] Quarry Moor,[20] and Bishop Monkton Ings.

[22] Although the former quarry pit Hay-a-Park Lake may be deep, Natural England recommends that the presence of any shallow water areas be maintained.

[nb 2] Some visitors to Hay-a-Park have been carrying out three categories of "operations likely to damage the special interest," namely articles 16a, 27 and 28 of Natural England's views about management of the SSSI.