Natural organic sorbents: peat moss, straw, sawdust, feathers and even ground corncobs can soak up 3-15x their weight, but may sink. Natural inorganic sorbents like clay, perlite, glass wool, sand or volcanic ash all can soak up 4-20x times their weight in oil.
Synthetic sorbents are similar to plastics and are designed to soak up liquids into their surface and can absorb up to 70x their weight in oil.