The active volcanoes are cool to see but the landscape on the Big Island is dotted with plenty examples of where the earth has had a previous effort at disgorging its contents. The mountains of Mauna Loa and Mauna Kea look exactly like you would expect a volcano to look with a nice big flat conical structure. However, the eruptions have not all come from the top of the mountain. There have been regular eruptions from weak points along the surface of the mountains and these eruptions have left their mark in more ways than just the lava flows scarring the slopes below them.
When the lava breaks out, it hardens as it reaches the surface. The deposits around the opening grow and you create a mini version of the mountain. These are called cinder cones. They are scattered all around the landscape and each was the site of a previous eruption. The center is hollow where the lava flowed out and sometimes the weakest side may have collapsed to leave the cone a little more exposed. The color of the rock can be pretty dramatic too. They look so benign now but at their most active peak, these places would have been spewing forth huge quantities of red hot molten rock. They would not have been a good place to be.