Well, you can't date those pictures very easily by the uniforms. Those guys hanging around the office could've been up at PACFLT last week, and the office would probably have the same coat of paint in it today. I'm pretty sure I was using that same chair in the 1990s. Khakis are no longer worn with ties like the group around the bay, but I don't know when that went out-- maybe in the 1980s. The Navy still issues those same glasses in the submarine force.
When I looked at the group by the water my brain immediately said "Hey, Hanauma Bay!" I think it's because of the bay's general shape and the fact that they seem to be standing on a dirt/grass bluff that overlooks the reef. If they were closer to the water they'd be standing on sand or coral. Hanauma Bay was largely deserted during WWII due to the coastal-defense patrols.
I hate to say this, but I agree with Omni that the picture is WWII vintage. The reason I hate to say it is because the hula dancers all appear to be of Portuguese/Caucasian heritage-- hardly an Asian or Hawaiian gene among them. Asian entertainers would've been a non-starter during this time and Hawaiians largely avoided performing hula in public back then. A picture in the 1930s or 1950s would have been much more ethnically varied and would have shown "real" hula, not the Kodak Hula Show variety. Today I don't think you could randomly photograph a halau that would look anything like that. Or such an ethnically homogenous office gang, either...
Other dumb questions-- are the backs of the photos marked with the paper's manufacturer, brand, or expiration date? Depending how the sheets were cut it might be spread across two of them. Are you able to determine what ranks your GFIL held and when he held them? That office photo looks like the office lieutenants posing for a shipmate shot. They wouldn't pose like that if an enlisted photographer was in the room.
If you really want to chase this down you might want to call Bishop Museum-- especially about the surf photo and the bay scene. They might be able to compare your GFIL's photos to their archives.