i have the capacity of 1 literbut all the water in the ocean can not fill me up.what am i?

a funnel?

You are a sieve or a colander. A sieve or a colander is a kitchen utensil that is used to strain or drain water from solid food items like pasta or rice. It has multiple small holes or perforations which allow water to pass through but not the solid particles. Since the capacity of a sieve or colander is typically less than a liter, all the water in the ocean will not be able to fill it up.