There are two types of ocean resources: living and non-living.
Some living resources include fish and algae. The fisheries turn out enough fish to feed 4% of the world's population, but recently, there have been overfishing problems, which occur when fish are caught faster than they can reproduce.
Just six species make up the majority of fish eaten: herring, sardine, anchovy, cod, pollack, and mackerel.
Algae is harvested for many purposes, like detergents, paints, shampoos, cosmetics, and even ice cream.
Non-living resources are also plentiful in the ocean. Some important non-living resources are water (obviously), salt, magnesium, oil, and minerals such as iron, gold, tin, and titanium. Some people even find diamonds under the ocean floor (lucky them!)
Natural gas and oil are extracted by huge oil rigs from the bottom of the ocean.
I think it is possible to overuse our resources, but I think it will cause problems, like how overfishing sometimes makes fish species extinct because they do not reproduce fast enough, and the environment will not work properly because of this.
For instance, if starfish go extinct, sea otters might die because they eat starfish. If sea otters go extinct, other sea creatures will be affected, thus messing up the ecosystem.