Aquatic mammals do not produce milk.

Answer

### Step-by-Step Solution:

1. **Understanding the Definition of Mammals**:
- Mammals are vertebrate animals that belong to the Phylum Mammalia. They are characterized by certain features, one of which is the presence of mammary glands.

2. **Role of Mammary Glands**:
- Mammary glands are specialized glands that produce milk. This milk is essential for feeding and nurturing their young ones, which is a defining characteristic of all mammals.

3. **Identifying Aquatic Mammals**:
- Aquatic mammals, such as whales, dolphins, and seals, are also classified as mammals. They possess mammary glands just like terrestrial mammals.

4. **Evaluating the Statement**:
- The statement claims that "aquatic mammals do not produce milk." Since all mammals, including aquatic ones, have mammary glands and produce milk for their offspring, the statement is incorrect.

5. **Conclusion**:
- Therefore, the statement "Aquatic mammals do not produce milk" is false because all mammals, regardless of their habitat, produce milk to nourish their young.

### Final Answer:
The statement is **false**. Aquatic mammals do produce milk.