Which one among the following is a sea without having a coastline ?

The Sargasso Sea is unique as the only sea on Earth that does not possess a land coastline [1]. Located within the North Atlantic Ocean, it is defined not by terrestrial boundaries but by four major ocean currents: the Gulf Stream to the west, the North Atlantic Current to the north, the Canary Current to the east, and the North Atlantic Equatorial Current to the south [2]. These currents form the North Atlantic Gyre, a vast circular system that traps marine plants and debris within its center [3]. While other seas like the North Sea, Baltic Sea, and Bering Sea are bounded by landmasses, the Sargasso Sea's borders are dynamic and entirely oceanic [2]. It is named after the 'Sargassum' seaweed, a holopelagic algae that floats and reproduces on the high seas within this region [2].

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > The Sargasso Sea – A Sea Without a Land Boundary > p. 492
2. [2] https://oceanservice.noaa.gov/facts/sargassosea.html
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > Influence Of Wind (Atmospheric Circulation) > p. 487