Seas: are the next largest. They’re usually salty and open to an ocean.
Gulfs: are large areas of water that penetrate into land, they usually open onto a sea or an ocean.
Lake: are smaller than gulfs and seas, usually have fresh water and are mostly or entirely encircled by land.
River: are large streams of water that empty into other bodies of water (e.g an ocean). The most important to tourism are the Mississippi ( North America), the Rhine and the Danube (Europe), the Nile (Africa), and the Amazon (South America)