The Singaporean tourist had jumped into a 4m-deep pool at the bottom of a waterfall in a park in Pahang, Malaysia.
But he got into difficulties and started struggling in the water.
When Malaysian tour guide Kevin Tan Chew, 42, saw his client in trouble, he immediately swam to the man's aid.
Mr Tan managed to rescue the Singaporean, but at the cost of his own life.
The tragedy occurred at the secluded Perting Pandak Waterfalls near Bentong, about 70km from Kuala Lumpur, on Saturday.
Visitors have to trek about 45 minutes to get to the waterfalls, also known as Lata Hammers. The water pours into a pond about the size of an Olympic swimming pool.
It was to this idyllic setting that Mr Tan and his partner, Mr Amos Ho, 29, took a group of 10 Singaporeans on that fateful day.
The two adventure guides run OpenSkyUnlimited, a small outdoor adventure company which they founded.
Recalling the tragedy, Mr Ho told The New Paper in a phone interview on Tuesday that it began as a routine trip to the waterfalls with their Singaporean clients.
After they arrived at the Lata Hammers recreation centre, everyone had fun in the water. The waterfall pool was deep enough for the tourists to jump into from rocky outcrop.