The Citadel of Spiders is likely the first cave you can go into easily in the Perplexing Pool region. It is just as simple as the White Flower Garden and Hole of Beasts in the Awakening Wood, with mild enemies and a mildly strong boss. To get to this cave, no trouble is required, just move straight out of the vicinity of your landing site, and move to the left, defeating one or more Yellow Wollywogs and some Shearwigs when needed. There are Skitter Leaves near the hole, but they can't bother you, so ignore them. This cave should be easy, so it would not be needed for you to go out of your way to stock on sprays, just get some nectar for your Pikmin so they'll be in good shape.