Gas.
The opposite of water resistance would be water permeability, meaning that water can easily pass through or penetrate the material.
The opposite would be to desaturate or unsaturate. For water, the opposite could be to dry.
The opposite of still water is gaseous or "sparkling" water. Technically though there is no "still" water if the opposite is gaseous water. The reason for this is that most most water known as "still" water contains quite alot of dissolved gas. Put simply the opposite of still water sparkling, that it's gaseous contain can be seen and/or felt as sensation in the mouth.
unpotable water
when the water is the opposite of hot -__-
Gas.
The opposite of an island is a pond because an island is surrounded by water and a pond is water surrounded by land.
the opposite of hydrophobic is hydrophylic
Possibly desert.
water
Water as a chemical compound has no direct "opposite."However, in the classical "elements" of nature, its opposite would be fire. Thermodynamically, the actual form would be ice.In earth sciences, surfaces that are not predominantly water are called land, although many overlapping environments exist.
The opposite of hydrant (water-releasing structure) could be: -- drain (where water goes, i.e. back out) -- inlet (where water enters the system, as opposed to where it exits)