For more than 300 "ice miners" in Harbin, work begins in the numbing cold before dawn every day on the frozen Songhua, a broad river that winds its way through the northeastern Chinese city.

Workers build ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 16, 2020.

Wielding long ice picks, the workers break up the frozen surface of the kilometer-wide river into crate-sized blocks of ice.

Workers build ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 17, 2020.

Many of the workers are construction laborers or farmers. They wear knee-high rubber boots, down jackets, thick gloves and hats with flaps to protect their ears from the frigid air.

A worker carries a block of ice while building an ice structure at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 16, 2020.

Every day since early December, tens of thousands of ice blocks have been prised out of the river and moved by truck to the venue of Harbin's annual winter festival, where they are used to build life-sized castles, pagodas, bridges and even a functioning hotpot restaurant.

A worker uses a chainsaw to carve a block of ice while constructing ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 16, 2020.

Workers wait to be served lunch at a food stall selling dumplings and buns outside the site of the Harbin International Ice and Snow Festival, before its opening in Harbin, China, Dec. 17, 2020.

Workers build ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 18, 2020.

Workers smoke while constructing ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 18, 2020.

A worker places a strip of light into blocks of ice while constructing ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 18, 2020.

A worker holds his chainsaw as he poses for a photograph while constructing ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 16, 2020.

A truck driver sits in his cab as blocks of ice to be used for the Harbin International Ice and Snow Festival are loaded onto his truck, before being transported to the site of the festival from the frozen Songhua River in Harbin, China, Dec. 15, 2020.

A worker stands on a block of ice block while breaking it into smaller pieces to be used at the Harbin International Ice and Snow Festival, at the frozen Songhua River in Harbin, China, Dec. 16, 2020.

Workers build ice structures at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 17, 2020.

A worker uses water to bond blocks of ice while building an ice structure at the site of the Harbin International Ice and Snow Festival, before its opening in Harbin, China, Dec. 17, 2020.

Workers place an ice block onto an ice structure at the site of the Harbin International Ice and Snow Festival before its opening in Harbin, China, Dec. 16, 2020.

A worker uses a forklift to load blocks of ice to be used for the Harbin International Ice and Snow Festival, onto a truck transporting them to the site of the festival, by the bank of the frozen Songhua River, in Harbin, China, Dec. 15, 2020.

An aerial photo shows the nearly completed Harbin Ice and Snow World in Harbin, Heilongjiang Province, China, Dec. 22, 2020.