In this question, we are asked to identify which of the given options is not a natural harbor. A natural harbor is a sheltered area of water formed by a natural geography that provides protection for ships from the open sea.

Option 1: Bombay

Bombay, now known as Mumbai, is a natural harbor located on the western coast of India. It is surrounded by islands and has a deep, well-protected bay, making it a natural harbor.

Option 2: Mangalore

Mangalore is a natural harbor located on the western coast of India. It is situated at the confluence of the Netravati and Gurupura rivers and has a natural channel for ships to enter, making it a natural harbor.

Option 3: Marmugao

Marmugao is a natural harbor located in Goa, India. It is known for its deep harbor and sheltered water, making it a natural harbor.

Option 4: Vishakhapatnam

Vishakhapatnam, also known as Vizag, is a natural harbor located on the eastern coast of India. It has a large, well-protected bay, making it a natural harbor.

Given the options, option 2 (Mangalore) is incorrect because it is