Drill holes to measure ice thickness before stepping onto it; don’t go out if it’s under 15 cm thick. Avoid ice over rivers and near ice-fishing holes

The easiest and cheapest option is to visit a properly managed public ice rink. If you must venture onto natural ice, bring an ice auger or ice chisel to measure thickness, plus a pair of rescue ice spikes — essentially two pointed spikes with handles that you can attach to your chest. Altogether, these items cost anywhere from a few dozen to a couple hundred yuan. You’ll need to measure the ice at regular intervals, which takes extra time.

According to the China Meteorological Administration, ice must reach 15 cm thickness before adults can skate on it, and outdoor rinks must also meet this standard to open. The Beijing Municipal Water Authority adds that natural ice rinks must have 15 cm of ice, plus stable temperatures between -8°C and 1°C without strong winds for at least a week before they become safe. Natural ice often contains holes drilled by anglers, which rarely freeze shut again. Minnesota’s Department of Natural Resources specifies that only transparent, newly formed ice under 4 inches (≈10 cm) thick is safe for walking or ice fishing; white ice formed after snow melts is only half as strong, so its thickness must be doubled. Ice thickness can vary dramatically across a single water body — sometimes 12 cm in one area and just 2–3 cm a few feet away. Ice over flowing water is especially hazardous, particularly near streams, bridges, and culverts; shore ice is often thinner than ice farther out. The U.S. National Weather Service sets the same minimum threshold of 4 inches for walking, ice fishing, and skating. The Canadian Centre for Occupational Health and Safety cites the Canadian Red Cross: groups of skaters or walkers need at least 15 cm of ice, while larger gatherings require 20 cm. These are safety guidelines only; no studies have quantified how many lives they actually save (nationwide, in the U.S. and Canada).

中国气象局 (2019). 想要冰上健步走，多厚的冰才安全？ https://www.cma.gov.cn/kppd/kppdqxyr/kppdtyqx/201901/t20190124_513302.html；北京市水务局 (2024). 北京正规河湖冰场还未达开放标准，别冒险滑「野冰」. https://swj.beijing.gov.cn/swdt/ztzl/fnsbaqztxc/fnszlxx/202412/t20241226_3973959.html；Minnesota Department of Natural Resources. General ice thickness guidelines. https://www.dnr.state.mn.us/safety/ice/thickness.html；Minnesota Department of Natural Resources. Ice safety. https://www.dnr.state.mn.us/safety/ice/index.html；Minnesota Department of Natural Resources. Steps for surviving immersion. https://www.dnr.state.mn.us/safety/ice/survival.html；National Weather Service. Winter Weather Safety: Ice and Frost. https://www.weather.gov/safety/winter-ice-frost；Canadian Centre for Occupational Health and Safety. Working on or near Ice Covered Water - Basic Information. https://www.ccohs.ca/oshanswers/hsprograms/work_ice.html

All official guidelines agree that no ice is 100% safe; reaching the minimum thickness is merely a baseline, not a guarantee. Early winter and late spring pose the greatest risks. If you fall through the ice, don’t remove your clothes — trapped air in thick layers can help you stay afloat. Turn back toward the direction you came from; ice there is usually the sturdiest. Place your arms on the surface, drive the ice spikes in, and kick your legs to pull yourself up. Once out, don’t stand up; roll flat away from the hole and seek warmth immediately — severe hypothermia requires medical care. If you see someone else fall in, do not rush to pull them out; follow the advice in Section 13, Item 25 (responding to drowning without entering the water): call for help, dial 110, then throw a pole or rope. The primary beneficiaries of these precautions are yourself and any children you bring ice skating.