As mentioned in the Volcanoes National Park page, the Chain of Craters Road follows the lava flow path from KÇlauea (and others) down towards the ocean. But normally the road is blocked before getting there with recent lava flows. Luckily, there is a way to get 'near' where the lava pours into the ocean by coming in along the coast.
This is something that should be done in the afternoon so that the dramatic scenes can be seen during the day and then well after sunset.
The road goes over some interesting lava flows (you can almost see it still flowing) and ends up in a narrow parking area, which you must back into. The idea is for quick evacuation - just in case.
You walk across more lava flows where you can see the swirls in the rock as the thick liquid solidified. You aren't allow too close and signs remind you not to lean against the barricades. The park ranger explained that there are glass shards embedded into the wood from the explosive force of the lava hitting the cold water. So if the wind changes direction, it is basically time to leave without argument.
Watching the huge plume of steam and gases from the meeting of super hot liquid rock and the cool Pacific Ocean is amazing. Occasionally puffs of horizontal steam eject sideways from explosions.
As the sun goes down this steam and gas cloud starts glowing red. Once it is dark, you can watch bursts of glowing material shoot out from explosions against the constant flow of the lava flow itself.