Why God does not like sea?

Sea / Ocean / Waters can be actual or metaphorical.

God "hates" no part of His perfectly good creation.
He "hates" sin.

In Revelation, the sea references the gentile nations. Guess what the land references?

God is not talking about bodies of saltwater or rivers of freshwater even though He uses them in allegory to help your understanding.

The seas stand in contrast to the rivers of living waters. Living waters are defined for us in John 4:5-28 in the conversations between the Samaritan woman at the well and Jesus.

So, if "sea" is to stand in contrast to that, then the disappearance of the sea means the second death will be overcome and therefore nonexistent for God's people.