Whale watchers look the opposite way as a monster mammal looms a foot behind their tiny boat.

Luckily they were Moby quick to turn around when alerted by another vessel.

These avid whale watchers nearly missed the moment of a lifetimeCredit: Caters

A sneaky whale popped up right behind their boatCredit: Caters

One raised arms in triumph as they captured the moment of a lifetime off Mexico.

Snapper Eric Smith, 49, said: “She slowly and silently stuck her head high above the water to look around.

“I was in another panga a few dozen feet away and caught the moment right before everyone realized she was so close.

“When everyone turned around, she quickly sank below the surface. Cheering and hysterical laughter ensued.

The watchers nearly missed the spectacular encounter by looking in the opposite directionCredit: Caters

Luckily the sightseers turned around just in timeCredit: Caters

“Whale photography involves a lot of luck, but the key is to always be on alert and ready.

“On a whale watching voyage, it is easy to get complacent because there is a lot of waiting.

“It seems like the moment you let your guard down a spectacular breach occurs.”

The whale was less than a foot from their boatCredit: Caters

The group were pictured waiting patiently with their cameras poisedCredit: Caters