Diego Martin is a town in northwestern Trinidad, just west of the capital Port of Spain and east of Carenage. The Diego Martin Valley in the Northern Range was once filled with a number of small villages but is now a densely populated area. It was named after a Spanish explorer Don Diego Martín. The area was first settled by French planters and their slaves in the 1780s. It consists of a cluster of villages including Congo Village, Diamond Vale, Green Hill, Patna Village, Petit Valley, La Puerta, Rich Plain, River Estate and Sierra Leone.
"Patna" reflects the settlement of Indo-Trinidadian indentured labourers, while "Congo" and "Sierra Leone" refer to free African indentured labourers. Places to visit include the historical Waterwheel and the Blue Range waterfalls, especially the magnificent Blue Basin waterfall.
The town area is administered by the Diego Martin Regional Corporation and is the home town of Miss Universe 1998, Wendy Fitzwilliam.