I think a geochemist would find the visitors center at Volcanoes National Park or the presentations/displays at the Imiloa Astronomy Center much more intriguing.

As for something to do in Hilo in the evening, well Hilo isn't a late night town ;)

There's always the mall or a movie.

The western half of Saddle Road is not only unpleasant but downright scary. The east side (newly re-paved) is fine -- but still has no banked curves. Be careful. It's always foggy a few miles mauka of the Hilo end.

I did 4 days on the BI with the little (no relations) a few weeks ago.

We flew into KOA, rented a car, spent a day & a night in the area.
We kayaked out to Captain Cook Monument, snorkelled with the honu at Kahaluu beach, and went down to the Heiau. (that was awesome; we arrived ~4:30 and had the darn place all to ourselves. Walked way out on the lava, saw some old fisherman's memorial and really enjoyed every minute of it. ^)

Then we drove around to VNP (right thru TS/TD Cosme) and spent 2 days & a night there.
Then went into ITO, overnighted there, turned in the car and flew back to HNL.
(note: don't plan on doing much in ITO on a Sunday; many places, including museums, are closed Sunday)(and it will rain :()

Find out if you can fly to one side, rent your car, return it on the other side & fly out from there.
Good luck!

And the entrance to VNP is at 4000 ft elevation
 

The entrance to VNP is at about 4000 ft elevation. My wife did this at 5 months pregnant and didn't have any problems, but I thought you would like to know. We stayed overnite 3 nights in Volcano as I recall.

My wife's biggest problem on that trip is that we got caught downwind from a strong sulfar bank at one point. My wife was concerned enough to call her O.B.

Enjoy the trip

I took the tour up to the top of Mauna Kea. Once was enough. It's a great place to go if you're into telescopes, but be prepared for cold, wind and perhaps altitude sickness. The tour companies provide everything you need to keep warm & oxygen in case you can't breathe :)

It was interesting to see, and boy was I hungry when I got back down, but I don't think I'd do it again.

No experience... but forget it. It's waay too high up there for a woman that pregant. You're talking over 14000 feet. The air is thin. Some people have trouble breathing.

I agree. And God forbid that something goes wrong. It's a long drive back down to Hilo Hospital.

That shouldn't be a problem, and it's not that far from Hilo. Here are a couple of expert views on the subject:

http://www.babycenter.com/plus/safe/...uestId=1137195

Another potential hazard for pregnant women to be aware of is the vog [as mentioned by OtisPDriftwood, above]. This caution is from the USGS:

What is "vog" and who is at risk breathing it?

"Vog" (volcanic smog) is the visible haze that forms when irritating sulfur dioxide and other volcanic gases combine and interact chemically with oxygen, moisture, dust, and sunlight. Kilauea emits about 2,000 tons of sulfur dioxide each day during eruption, now mainly from the still-open vent at Pu‘u ‘O‘o.

Trade winds commonly disperse the volcano's gases, so that the concentration is not generally hazardous. However, sulfur dioxide fumes can be concentrated near ground cracks along and down-wind from lava tubes.

Concentrated sulfur dioxide fumes put all people at risk, but particularly those persons with breathing problems (such as asthma and chronic obstructive pulmonary disease) and heart difficulties, pregnant women, infants, and young children. If sulfur-fume concentrations begin to cause you physical distress, you should leave the area.

Interestingly, there are days when the vog can be much worse in Kailua-Kona town than at the park itself.