Birch
Usually Birch.
Balsa wood is the lightest.
The lightest wood is typically considered to be balsa (Ochroma pyramidale), which is known for its exceptional lightweight properties and is often used in model building and crafts. The second lightest wood is usually called paulownia (Paulownia tomentosa), which is also lightweight but slightly denser than balsa. Both woods are valued for their strength-to-weight ratios, making them popular choices in various applications.
Common knowledge would say balsa, but there may be a lighter one out there. Cork is pretty darn light, but the light part is technically its bark.
The lightest type of wooden bat i have used has been Ash, it is very durable, light and has a good pop to it.
balsa
I'm pretty sure it's balsa wood.
Balsa wood is used
Balsa wood would float because it is one of the lightest woods available, with a density lower than that of water. Its low density allows it to displace enough water to support its weight, making it buoyant. This property is why balsa wood is often used in model building and lightweight structures.
A drill is commonly used for making screw holes in wood.
morning wood
Western cedar.