From Episode 103, as Matthew Mercer describes the interior of Vokodo's Lair:

Suddenly the narrow pathway expands, into a gargantuan underwater chamber. 
Where you can see the rough, black glassy volcanic rock, broken by heavy patches of torch bloom in corners giving of pockets of light, in an otherwise lightless room.

You can see pillars of the same volcanic rock, and gathered minerals, that vanish into small cracks. You can see heavy stalactites coming down from the ceiling. Some only a few feet, some from a 40ft ceiling some almost touch the rock, it is a jagged forest from upside down rock, coming from above. The rock walls glow faintly orange from the heat of volcanic proximity.

From edge to edge, from where you entering now, across the way, and from what you can see, you are not able to see the other edge. You see one edge of the tunnel, it's wall curving around one side the opposite side. There are platforms of volcanic rock, and there is a bridge of one growth as well. Elements of nearby rock created a small incline, which you can see on the opposite end.

It is a really wild interior here, and you’re free to swim if you like. A torch bloom has completely enclosed the tunnel behind you.

As you glance around, the first thing you notice, is that there is a couple of shiny glints in some parts of the floor. It looks like a coin, a gold piece that is just kind of catching the light, you see a few more, scattered about, a handful that are resting on an element of rock, scattered about in the cavern.

You glance up, and in the centre of the ceiling, amongst the heavy points of rock, you see a couple of other glints, Light reflecting of of other surfaces.