Substances with a specific gravity of NUMBER@1 are neutrally buoyant , those with SG greater than one are denser than water , and so -LRB- ignoring surface tension effects -RRB- will sink in it , and those with an SG of less than one are less dense than water , and so will float .

Substances with a specific gravity greater than NUMBER@1 are heavier than water , and those with a specific gravity of less than NUMBER@1 are lighter than water .
