Gently

Just to be clear, I thought I only had the one sunrod? --And it broke? If the team has another, they'll light it up. Otherwise, I think a second torch is in order.

Castille turns to his companion, "Kaspar! This stench is worse than you on a Monday. Careful not to fall in. I don't want to have to make Humfred swim after you."

After shining a bit more light around the cavern, Kaspar moves very slowly onto the catwalk, testing its strength and trying to spot the cause of the break.

A spot check for Kaspar here comes up 16+2=18.

As Kaspar approaches the body, he calls back for Castille's spear. "Give it quick. I'll fish him out. I think I can reach."

If Kaspar can reach the body using Castille's spear, then he'll drag it towards the catwalk, and then slowly back to the platform edge before taking it out of the muck. In this way, the least amount of weight will be placed on the catwalk.

However, before Kaspar begins, Castille turns to Humfred with a smile, "How well do you swim?"