In this video, explorers visit a Hawaiian volcanic site to not only see lava up close, but play with it. This appears to be both a fascinating and nerve-racking experience.
Video embedded with thanks from: Jeri Ellsworth on Youtube.
The temperature of lava normally ranges from 700 (1,292 °F) to 1,600 °C (2,912 °F). It is therefore hot enough to kill you if you get your foot stuck in it, for example. Large scale lava flows can decimate an entire village, not only because it will burn it, but it is also extremely heavy and viscous (dense and syrupy).
When it cools, and hence hardens, whatever was trapped under it is no longer recoverable. The lava exploration in the video above may not look particularly dangerous, but, it has to be done with great caution because you may not see little crevices that hot lava are in, between hardened rock. Your feet may slip into them.
Learn more about volcanoes here.