Read these lines from Canto xxii so here on all sides these sinners squatted but the instant barbariccia stepped forward they dived back underneath the boiling pitch I saw and still Mt heart shudders with it one lag behind just as sometimes one frog will stay back while another leaps below and Graffiance the closest to him hooked him up by his pitch knotted hair and hauled him out he looked just like an otter! What is dante describing here?

Dante is describing sinners suffering in boiling pitch. Their suffering is eternal; they suffer in the pitch, and they suffer when they break the surface.

There is a pool of boiling pitch that the souls bob in and out of. When they break the surface, a demon grabs them and tears them apart. By remaining under the pitch for as long as possible, they can escape the demon's tortures and gain a form of peace. (This is a relative form of "peace" because they are still submerged in boiling pitch.)

When a demon does pull a sinner out, Dante describes him being pulled out by his hair. The demon, with the sinner hanging out of his mouth, appears to look like an otter.