Waterproofing the iPhone 7 Plus for use in sea water

I use an iPhone 7 Plus with an Overboard waterproof bag. I take a lot of photos and the waterproof bag is very cumbersome. I've noticed the only holes in the iPhone are the charging port and the speakers. The rest of the iPhone looks sealed. If I put tape over the speakers and charging port, will that be enough waterproof my iPhone 7 Plus? Are there any other "holes" in the iPhone?