on (the) land
Physically located on the ground or a body of land, as opposed to the water or the air. Many amphibians split their time living on the land and in the water. I got so terribly seasick on that cruise, so it's nice to be on land again!
on land
on the ground; on the land and not at sea or in the air. The flight was rough and I feel better now that I am back on land. When l am at sea, I feel more relaxed than when I am on land.