The Crossing of Ingo is a children's fantasy novel by Helen Dunmore, first published in 2008.

It is the fourth and final volume in the Ingo tetralogy.

[1] Sapphire and Conor have been called to make the dangerous Crossing of Ingo, a journey to the bottom of the world, and it has been prophesied that if they complete it then Ingo and Air will start to heal.

They have their Mer friends, Faro and Elvira, to help them, but their old enemy, Ervys, is determined to make sure they don't succeed.

The book has received positive reception from the Liverpool Echo and The Times,[2] the latter of which described it as "a dramatic climax" to the series and picked it for a summer reading selection for 2008.