The dinosaur extinction is widely attributed to a large asteroid from space, hitting the earth near Cancun, in the Yucatan peninsula / Gulf of Mexico. This 10 km diameter asteroid strike occurred 66 million years ago, with the center of the impact near the coastal town of Chicxulub which is about a 5 hour drive from Cancun. The resulting splash wave is estimated to have been 1.5 km high, with resulting mega-tsunami of 100 Meters, reaching USA in Louisianna / Florida, Cuba and Haiti.
The impact spewed hundreds of billions of tons of sulfur into the atmosphere, producing a worldwide blackout and freezing temperatures which persisted for at least a decade. Some of the ejected material was bounced up outside the earths gravitation escaping back into outer space again.
Wikipedia has a lot of good information about the current known information: Chicxulub crater – Wikipedia
Also more of a geological perspective: Chicxulub Impact Event (usra.edu)
NY Times article: Drilling Into the Chicxulub Crater, Ground Zero of the Dinosaur Extinction – The New York Times (nytimes.com)
Trip Advisor advice re visiting: Chicxulub crater: How to visit the dinosaur-ending asteroid site in Mexico – Tripadvisor