At time of booking the Volcanoes National Park would have been one of the very big highlights of our trip, as places with volcanic craters, a lava lake and active lava flows, while still being easily accessible, are hard to find elsewhere in the world (therefore this place is also called “drive-in volcano”).
Now, the park changed quite a bit between May and July 2018:
“Beginning in May, 2018, the lava lake that existed inside Halema‘uma‘u crater disappeared and lava flows from Puʻu ʻŌʻō crater have ceased. There is no molten lava or lava glow to see anywhere in or out of the park.”
A highly recommended movie about the events here:


https://www.nps.gov/havo/planyourvisit/lava2.htm
But on the positive side, the park had re-opened (after another closure due to government shutdown in January, just a few weeks before our visit). Even without molten lava the park was still worth a visit: the Kilauea Caldera is still impressive. The views on lava flows of the 70ies are also nice to see, and a hike over the Manua Ulu eruption(s) (1969 – 1974) on hardened lava structures is a very extraordinary experience.