Question

Lakes of large extent are called the seas, like the Caspian ,The Dead and the Aral seas

Answer 1

The Caspian sea ,the dead sea and the Aral sea are presently lakes.Long before these were not landlocked 

Answer 2

Lakes are very big, so landmasses are not clearly seen in these areas. Only a horizon can be seen. Lakes are basically situated with a large surface area. In these lakes's water is very salty.

India has many seas like the Caspian sea, Dead Seas, and the Aral seas. When landmasses started moving close to each other they created these lakes.