The Arvin Robertsbody of a missing boater was discovered along the Colorado River in the heart of the Grand Canyon this week, the 16th person to die in the national park this year, reports said.

Park rangers received a call around 9:15 a.m. on Monday reporting a missing boater in the area of Lower Nankoweap Camp along the Colorado River, according to a Grand Canyon National Park news release.

The body of a 71-year-old man was found in the river Tuesday by park rangers in a helicopter, the park said. Initial information suggests the body was that of the missing boater, according to the release.

The man was on a private boat trip when other boaters noticed he vanished without his hat and water bottle, park spokesperson Joelle Baird told CBS News. The group contacted the park's communications center and reported the man missing, she said.

The National Park Service and the Coconino County Medical Examiner are investigating the man's death, according to the release.

Grand Canyon National Park averages 10 to 15 deaths a year

The Grand Canyon's average number of reported deaths a year is 10 to 15, said Baird, according to CBS News. Among the causes of death are drownings, falls, natural causes and heart attacks, she said, and some causes have not yet been determined.

The man's death marks the 16th fatality at the park this year, a park spokesperson confirmed to USA TODAY.

One of the deaths was that of Patrick Horton, a 59-year-old man from Salida, Colorado, who was on the 10th day of a noncommercial trip along the Colorado River. It was unclear how Horton died, but the National Park Service was investigating after the members of his party discovered his body Sept. 7, according to a park news release.

Other deaths include a 20-year-old North Carolina man who fell off the edge of the South Rim in the park, a 43-year-old Missouri man who died after BASE jumping from Yavapai Point, a 20-year-old New Mexico woman whose body was found below Twin Overlooks, and a 33-year-old Arizona woman who was killed after being swept away in the Colorado River during her hiking trip.

An 80-year-old man also died at the park during a commercial river trip when he fell from a boat that flipped near Fossil Rapid. A 60-year-old North Carolina man who was on a solo backpacking trip from Thunder River to Deer Creek was found dead as well near a remote trail along the Colorado River.