The Aqua Line is a name common to a number of rail systems around the world. It can refer to:
- Aqua Line (Mumbai Metro) Mumbai, Maharashtra, India
- Aqua Line (Noida Metro) Noida, Uttar Pradesh, India
- Aqua Line (Nagpur Metro) Nagpur, Maharashtra, India
- Aqua Line (Pune Metro) Pune, Maharashtra, India
- Aqua Line (Namma Metro) Bengaluru, Karnataka, India
- Canada Line Vancouver, British Columbia, Canada
- E Line (Los Angeles Metro) Los Angeles, California, United States of America
- Tokyo Bay Aqua-Line Tokyo Bay, Japan
- Mexico City Metro Line 4, Mexico