The property of water that helps to regulate Earth's temperature is its high specific heat. This means that water can absorb and store large amounts of heat with only minor changes in temperature. This property is crucial for maintaining stable environmental conditions, as it allows large bodies of water, such as oceans, to moderate the climate of surrounding areas. Consequently, regions near large water bodies experience milder climates than those situated farther inland, highlighting the essential role of water in regulating not just local but also global temperatures.