Bluewater spearfishing can be the most boring type of spearfishing at times. Unlike reef diving where there is a lot more life swimming around and nice corals to look at. Blue water is all about patience and capitalizing on opportunity. We normally spearfish blue water less than 300ft of water. Other places we go deeper, a lot deeper!
Drop your flashers, drop some chum and sit and wait. Most times chumming you'll invite a few land lords (sharks) up your chum line. On Oahu, we target Mahi, Ono (Wahoo), Shibi (an Ahi that is less than 100 lbs) and if you're really lucky you may run into a sail fish or marlin, even in the shallows.
I'm not sure how it is everywhere else in the world, but here on Oahu some days we go out and we don't see anything at all. & other days a fish or two may pass giving you one chance to take a shot or sometimes not even a shot at all.
& other times, the day is non stop action and everybody is picking up something good! Not many times is like this, but these are the days you never forget.
The most memorable pelagic fish I've show is a 47lb Shibi or Yellow Fin Tuna. We did blue water all day hanging out in 100-200ft water. We didn't see anything at all. With chum to burn and the sun setting low we jumped in one last time in about 30 ft water. I brought some chum with me for chance for Ukus (Green Job Fish) and I was embraced with a big Shibi. Took my shot and the rest is history.
The video of the beast and more memorable blue water spearfishing catches including a 50lb Ono is in the compilation video below titled "Blue Dreams"