Dante's Inferno, trans by Sean O'Brien

Sean O'Brien is surely right to claim that Dante's Inferno "is the most frequently translated poem in the Western tradition". His version, arriving just a few months after that of Robin Kirkpatrick (The Divine Comedy, Penguin, £10.99), is a further confirmation. Both employ blank verse. Otherwise, the translations could not be more dissimilar. As far as I could see, the only thing that reads identically in both versions is the beautiful line, with its ripple of "o"s, describing the foul Harpies "who drove the Trojans from the Strophades".

Although the Italian "hendecasyllable" line is often much longer than 11 syllables, as adjacent vowels don't count, the pentameter would seem the natural English choice for Dante, and has been employed again and again in translations. Dante's metre, though, secures very different effects: its unstressed final syllable, combined with its interlocking rhyme-scheme, the terza rima, gives it the capacity for greater forward propulsion and pace. That is a useful attribute in a poem so shaped by continuous walking, climbing, wading, sailing and flying.

Kirkpatrick's translation (accompanied by a dual text and excellent introduction and notes) is the odder, the riskier of the two. His treatment is surprisingly free and improvisatory, though always prompted by a strong sense of the original. Lines such as "Our tread now fell/ on voided nothings only seeming men" make something inventive and strange out of the iambic beat.

O'Brien has formidable skill with the pentameter, and gives it a stately, marmoreal quality emphasised by the way Dante's terzine are laid out as three-line stanzas, and each canto given a title. Some of the finest moments occur when this disciplined and chiselled line sparks against obdurate matter with grim energy: "The demon Charon, with his eyes like coals,/ Then summons each to take his place aboard/ And clubs the laggards with his dripping oar."

The language is deliberately plain, without being plodding and tuneless. O'Brien often deploys runs of monosyllabic words to impressive effect: "I saw a broad ditch bent into an arc,/ And seeming to encompass all the plain,/ Just as my guide had told me that it would."

This landscape from Canto XII perfectly prepares the reader for the arrival of the centaur archers, and their leader Chiron, who takes "An arrow out and with the notch of it/ Brushed back his heavy beard upon his jaws". In both instances, the English does justice to the original.

One testing problem for a translator is the way Dante's poem keeps developing, and each canto extends its voice and voices. The Wood of the Suicides, for example, introduces the courtier Pier della Vigna, whose spidery, intricate wordplay is a translator's nightmare. The whole canto is knotted with these ingrown resonances - even Dante himself is not immune, with his line: "Cred'io ch'ei credette ch'io credesse", which Kirkpatrick quirkily renders as "Truly I think he truly thought that, truly". O'Brien, more straightforwardly, has "It seems my master thought that I believed".

What O'Brien has achieved is a compellingly readable version of the whole poem, with a steady incandescence to the language. Any reader with no Italian could do a lot worse than turn to both new translations; and readers who know the original could still learn much from them.

Jamie McKendrick's collection 'Ink Stone' is published by Faber