We are taking our honeymoon in November and buying our plane tickets now. We have five days in Hawaii and then five days in Kauai. What is the best way to get from Hawaii to Kauai? Should we plan for that now and book the plane tickets ahead of time or just wait until we get to the islands and figure it out from there? We also thought we heard something about a high-speed boat that could take us from one to the other? I knew someone here would have advice on the best way to do it!
The two islands are hugely far apart. A boat just won’t cut it. Take a plane.
Fly. And you might as well get the tickets now, rather than wait till possible fare increases.
I take it you don’t want to take the bus? 
But yeah, take a plane. It’ll be expensive, but there are commuter flights you can probably take advantage of.
Probably not the case anymore, but when we went to Hawaii in 1999 on American, you could get one flight to another island and a return from that island at the same price as a round trip to a single island.
Isn’t flying to one place then returning from there the exact definition of a round trip?
I expressed myself poorly. When we went, the Boston -> Oahu round trip cost exactly the same as Boston->Oahu->Maui->Boston. The airline rep I spoke to told me they do that on purpose.
You are probably referring to the Superferry. It is not an option for you for Oahu > Kauai travel, as the Superferry currently only travels to Maui. Big Island service is scheduled for 2009. Kauai service AFAIK has not been announced, but it’s likely to be the next island served.
Besides, it’s asstacularly slow, taking 3 hours to get to Maui, which is roughly six times the time it takes to fly there.
Buy your plane tickets now! 
I don;t have a sense of how far apart the islands are. Can you see one from the next?
Well, there’s the problem. It’s a three-hour tour, a three-hour tour.
Fly.
Check Hawai’ian airlines or Go! airlines. Both depart from either Kona or Hilo on the Big Island. I have absolutely no cite when I say that it might be safer to book with Hawai’ian over Go! in case Go! goes under (as Aloha airlines recently did).
Where are you staying on the Big Island?
AFAIK, no, you can’t. It’s about 300km from Hawaii to Kauai, about the same distance as Boston to Baltimore.
(Eyeballing on Mapquest. Maybe my eyeballs need to check their math, though.)
I’m not entirely sure if you’ve booked your flight from the mainland yet, but you should definitely consider a multi-stage (used to be called open-jaw) booking. Fly from home to Big Island then Kauai to home. Also, you definitely want to book your commuter flight from the Big Island to Kauai now, not once you are there. I think I used Go!, who I thought were a subsidiary of one of the big airlines. Maui to Big Island (during Christmas, no less) was about $90 +tax etc., which is silly cheap for anything in Hawaii.
I misread the OP and assumed they were starting in Oahu. But the point still stands that the Superferry is not an option.
I read it is about 350 miles between Kauai and the Big Island. Seems about right, as they are at opposite ends of the chain of main islands.
Even if you could take a boat, you probably wouldn’t want to be on it that long.
Okay! Thanks for the consensus. RWS, we are staying at my mom’s timeshare through Trendwest on both islands.
I feel silly for not knowing that the islands were so far apart… They look so little and close together on the globe. 
We will order all the tickets together. Sounds like it might be easiest to go through a travel agent so they can book them all and maybe get us a deal.
Thank you!
I went to Hawaii with my family in 1976; I was 11 years old. The only flights from the mainland were to Honolulu (Oahu) and Hilo (Hawaii). I’m surprised they fly direct to Maui now, although the airport back then could handle 737/DC-9 class aircraft, so it’s not out of the question.
We flew between islands, except with took a hydrofoil from Kauai to Oahu. Cool trip. I remember the captain (or somebody) mentioning that that was the only inter-island trip where you’d be out of sight of land (at the midpoint, you can’t see either island).
Continental runs regular service between Maui and Houston.
You can see Hawai’i from the south coast of Mau’i on a good day, and vise versa. I’ve stayed on Mau’i’s south coast several times, and driven up Haleakala. From south Mau’i you can see lights on Hawai’i at night, though I’d never seen the other island in the daytime from that coast. From the top of Haleakala you can see pretty much the whole island of Hawaii.
I would guess you can see Molaka’i from the north coast of Mau’i, given good conditions, but I haven’t witnessed that. Kaua’i is a pretty fair distance from its neighbor Oahu, so I’d guess you can’t see one island from the other.
Comparison map here, note the scale of the map. Oahu to Kau’i looks to be about 60 miles. Hawai’i to Kaua’i looks like maybe 190 miles.
Well, one of our favorite stories involves a couple of Big Island tourists who asked our neighbors where the bridge to Maui was, because they were planning to drive there…