Oakwood is very soft and light, with a coarse, open grain. The density of dry balsa wood ranges from 40 to 340 kg/m3, with a typical density around 160 kg/m3. Balsa is the softest wood ever measured using the Janka hardness test (22 to 167 lbf). The wood of the living tree has large cells that are filled with water. 
USE:
Oak is used to make wooden crankbaits for fishing, especially Rapala lures.Sticks of dried balsa are useful as makeshift pens for calligraphy when commercial metal nibs of the desired width are not available.Balsa wood is often used as a core material in composites; for example, the blades of many wind turbines are partly of balsa. In table tennis bats, a balsa layer is typically sandwiched between two pieces of thin plywood made from other species of wood. Balsa wood is also used in laminates together with glass-reinforced plastic (fiberglass) for making high-quality balsa surfboards and for the decks and topsides of many types of boats, especially pleasure craft less than 30 m in length.