He's right ya know.
The Great Lakes and the inland waterways of the NE are loaded with wrecks, most of which are fairly intact. These are a huge part of what helped this country get built and stay ahead.
The West coast has the Channel Islands, their kelp forests and some incredible beach dives from San Diego to Puget Sound. Sea lions, otters and giant octopus not to mention giant Black Sea Bass that are frequently haunting known locations and can be seen almost on cue.
Warm water is great, but just a bit of a thicker wetsuit will open your eyes to underewater wonders.