A guest who saw two bodies in a hotel pool thought they there were part of a murder mystery event, an inquest heard.
Komba Kpakiwa, 31, and Josephine Newahun Foday, 22, died at the luxury Down Hall Country House in Hatfield Heath, Essex, in April last year.
Marcel Haniff told an inquest he saw the couple playing in the pool minutes before returning to see their bodies.
"There was a murder mystery weekend at the hotel so I thought it may still be a prank," he said.
Mr Haniff, from Hertfordshire, told the inquest in Chelmsford that he had gone for a sauna after seeing the couple engaging in "horseplay".
"They seemed to be perfectly healthy and just shouting and playing," he said.
The inquest heard how he returned to the pool and initially thought the couple's lack of movement was part of a game, but soon realised something "was seriously wrong".
"I ran back to the reception to tell them what had happened," he said.
A post-mortem examination found Mr Kpakiwa, from Erith, and Miss Foday, from Plumstead, both in south-east London, died from drowning.
Neither could swim.
The inquest heard the pool was not manned by a lifeguard and a CCTV camera that covered the area was broken.
The inquest is expected to last three days.