Breast-deep is a phrase used to describe the depth of water, typically when someone is wading or swimming. There are several synonyms for breast-deep that can be used to add variety to your writing. One option is waist-deep, which indicates water that is deep enough to reach the waist of a person standing in it. Another synonym is chest-deep, which is similar to breast-deep but indicates water that is even deeper. Thigh-deep is also a common synonym, indicating water that reaches up to a person's thighs. Finally, shin-deep is a useful synonym to describe shallow water that only reaches up to a person's shins.