"That is a crock of rancid yak butter," said a voice from the ship.

The monastery is also famous for its sculptures of human figures, animals and landscapes carved out of yak butter.

Tea is mixed with yak butter for a high-calorie drink in this shivery climate.

The most unusual sight in the monastery is the 50-foot-long carving made of yak butter.

The market also sells yak butter, cheese, wooden bowls and fabrics.

The steps were slick with the yak butter that fuels the flickering lamps.

Sweeper dropped a lump of rancid yak butter in the tea bowl beside him.

It is made from tea leaves, yak butter, and salt.

The air is heavy with the smell of yak butter, sweat and incense.

Today Tromzikhang market sells items such as yak butter, cheese, tea, noodles, vegetables and candy.