Past Penquins, Can't cross River of Sludge

[Rattsukrabe]

This stumps me. I would like just a hint. I think I may be missing some inventory, but cannot imagine what it could be. I have tried various ways to nab one of the "trees" to use it to cross the river, but that has not worked. I have an, um, "item" that can slide, but that has fatal results. Is it something really bizarre? I cannot figure it out.

[mjomble]

In addition to using an item, you need to grab the ladder at the right moment.

[Rattsukrabe]

Thanks! Just finished kicking myself for not figuring it out myself.