Awesome diving! I've only been to Tulagi (an hours boat from Honiara)but there are tons of wrecks from the battle of Guadalcanal. I was there for the this year's Guadalcanal ceremonies so it was quite special when each wreck had a story along with actual war veterans talking about their experiences.
Don't expect any modern conveniences. SI is much safer than PNG but it's still Melanesia and can erupt suddenly, so be sure to have travel insurance, etc.
I did my dive w/ Neil Yates at Tulagi Dive. He's a really cool dude and will tell you all sorts of stories of wreck diving. There is the AARON WARD which is at 70 meters that you dive on air...yes, on air, because there is no mix-gas facilities. I didn't do it since my max is 43m and I want to take deep diving and also experience a bit of getting narc'd before hitting the WARD.
SI is definitely an adventure and it's absolutely stunning. Have fun!
