I've used a "waterproof" marine tool kit on small boats, and most are merely water resistant. Eventually, the water and salt get in, and your tools get ruined. I went through lots of tools. I could not find a tool box that could survive on a small boat and keep the tools separate from the water and salt.
I gave up and bought a Pelican box. It's worth every penny. My Pelican marine box is sturdy and completely airtight, not just waterproof. I have had mine for ten years now, and the only time water got in was on one occasion when I inadvertently closed a plastic tie-wrap in the lid, preventing the gasket from sealing. Before I bought the Pelican box, my tradition was to find out that my tools were rusty and unusable when I actually needed them. It's nice to open up my Pelican case knowing all will be well inside.
There a lot of Pelican cases available in different sizes for just about any purpose, not just boating. I have one for my small-boat toolkit and one for my video camera. My wife has one for her iPhone, and another small-ish one just big enough to hold the phone plus a few other small items. Most Pelican cases come with foam inserts to protect your digital camera, video camera, or other gear. Most of them come with the "pick-n-pluck foam insert" that allow you to create exactly the number and size of the "holes" to fit and protect your specific gear.