Why are the conditions for the existence of organisms in the ocean more favorable than on land?

Why are the conditions for the existence of organisms in the ocean more favorable than on land? Where are the richest areas in the World Ocean?

Conditions in the ocean are more favorable than on land for the following reasons:
1) the absence of subzero temperatures and sudden temperature changes;
2) water, unlike air, better supports the body of animals and organisms, therefore, organisms with a large weight can exist in the ocean.
3) there are no droughts in the ocean, and all organisms need liquid in one form or another.
4) there are no winds in the oceans, so plants do not need thick roots to take root in the soil.
An important condition for the development of life in the ocean is the presence of oxygen. Oxygen in water is produced by algae, through photosynthesis, they absorb carbon dioxide and water and, in the light, convert it into oxygen and organic matter. Since sunlight cannot penetrate deeper, areas richer with life are located in the coastal zones of the equatorial belt, where algae receive more light and can produce maximum oxygen. Growing algae also serve as food for various organisms.