No need to apologize for using an asset pack, that's what they're for in the first place. I used one myself ;)
When I first hopped into the green "water" I was fully ecpecting it to be something dangerous, so I don't think it needs any extra introduction. It first appeared pretty close to a checkpoint as well, so no losing half a level of playing just right before the next one. As I said, level designs are pretty good!