It comes after officers and paramedics rushed to Southall Park, Ealing, shortly after 6am on Saturday following reports that a person was unresponsive.
The woman, thought to be in her 30s, was pronounced dead at the scene.
The Metropolitan Police said the incident is “still unexplained at present” and they are awaiting further results from the post-mortem.
An examination had been conducted on Sunday at Fulham mortuary but it did not establish a cause of death.
Police said steps are being taken to inform next of kin.
Enquiries are ongoing to establish the circumstances. Witnesses or anyone with information that may assist the investigation are asked to call 101 ref 1674/17JUL