Four students and a volleyball coach, all hailing from Thiruvananthapuram district, went missing from Kovalam beach on Saturday, police said.
Onlookers said the group did not heed the warning that swimming in the dark was dangerous.
An official attached to the Kovalam police station told IANS that the five were reported missing around 7 p.m.
"Of the five, four were from a group of friends, and the other (coach) was from another group. Except one who was in his early 30s, the others were in their 20s," the official said.
The Coastal Police department has launched a search operation.
