Shore diving on the Big Island ranks high among my favorite experiences in life. I've been lucky enough to visit 3 times and done almost exclusively shore diving each trip. I would recommend you visit at least a couple sites: Two-Step and Kona Old Airport.
Two-Step is about 30 minutes south of Kona proper and is a popular snorkeling site. Go early (true for all sites) and park in the church lot ($5, but worth it). The name refers to a natural formation in the rock that makes entry and exit easy (even with a camera). Even if you can't arrange a buddy beforehand, it's likely you'll find other people diving when you go. But it's an easy site to do solo. You can choose to go north or south, and you can choose your depth. There's usually little current and the bay is protected so things don't get too surge-y. But, go early anyway. If you stay shallow, it's easy to get 2 hours on a tank. Tons of typical hawaiian fish, possible spinner dolphins, turtles, eels, eagle rays. Lots of good photo ops. You can dive it wide angle or macro - good photo ops for both modes. This map marker shows the actual location of the entry:
Google Maps
Kona Old Airport is just a super cool place to hang out. Also best done early, there is plenty of free parking. The entry/exit is a little trickier, especially at low tide. Try to go at high tide if possible. Lots of interesting formations. I like to head north until a dropoff, then swing back south and do a circular path to end the dive. This map shows the location of the entry:
Google Maps
Same as above for photo ops.
Other sites I enjoy diving:
Pebbles (hour south of Kona)
Puako (hour north of Kona)
Mile Marker 4 (in Kona, parking hard and dive not as varied)
The local shops (Kona Honu, Jack's, etc. all have advice and equipment for shore diving).
Navigate The Amazing Reefs On Your Own Time. We Have Shore Dive & Snorkel Maps For Kona, Hawaii. Snorkel and Dive Using Our Maps for Hawaii.
www.jacksdivinglocker.com
The Big Island has a lot of really stellar scuba diving. Most of the western coast (Kona Coast) is really nice with calm clear water and plenty of marine life. That being said it can be rather…
konahonudivers.com
Have fun. Be safe. Enjoy. WIsh I could meet you there....