Willow logs are logs which can be cut from willow trees using the Woodcutting skill. Cutting willow logs from a willow tree requires a hatchet and level 30 Woodcutting, and grants 67.5 Woodcutting experience per log. Therefore, a full inventory will grant 1,890 experience.
With a Divination level of at least 32, 3 oak logs may be transmuted into 1 set of willow logs. This costs 2 glowing energy and yields 7.3 Divination experience.
Willow logs can be burned using the Firemaking skill and a tinderbox. This requires level 30 Firemaking, and grants 90 Firemaking experience per log, or 105 if adding willow logs to a bonfire. (135 experience if using a Firemaking ring.) In addition, members trained in the art of barbarian firemaking can light willow log fires with a bow instead of a tinderbox at level 35, also yielding 90 experience per log. They can also create pyre ships from willow logs at level 40 along with level 40 Crafting with a tinderbox or bow, a hatchet, and chewed bones or mangled bones, giving 22.5 Crafting experience and 90 Firemaking experience.
Willows can be a very cost-effective way of getting to 99 Firemaking. It takes no more than 118,105 willows to get from 30-99 Firemaking when burning them on a bonfire to which five or more players are contributing. This adds up to just 21,377,005 coins, however this process is very time consuming, so most players tend to avoid it.