The first reports of the underwater archaeology near Dwaraka were written by S. R. Rao.  He was an innovative archaeologist and managed to convince the Indian navy to work with him.  He did indeed find man-made remains of walls etc. underwater.  However, he was a staunch Hindutva supporter and promoted the idea that he had discovered Kṛṣṇa's original city.  I visited him, years ago, and I speak from personal experience of our conversation.  In my view, his published work is a mixture of excellent and innovative underwater archaeology and fanciful interpretation.