First of all, our captain and tour guide were very friendly, knowledgeable about the coastline and history of this particular area, and skillfully handled the boat. The boat is intimate with a total of 6 padded, comfortable seats that are on swivels, so that you can easily point yourself in the direction that you want to look.
The boat easily handled the 3-5 ft swells we experienced on our trip, and we did not get wet at all from any ocean spray (although, we did get wet in the rain that was at the boat ramp--but it's Hawaii, so the rain wasn't any problem for us). The front of the boat has a cabin and large windshield plus a small roof over the captain, and this deflected any spray from the boat going through the waves. The captain also guided the boat very well through the waves to minimize roughness and water spray.
We took the dawn patrol tour (first trip of the day), and we highly recommend this trip, despite having to get up and drive to the launch ramp and arrive well before dawn. It takes nearly an hour to get from the ramp to the lava viewing area (the coastline is covered in darkness, so not much to see except the stars above), and the pre-dawn/dawn lighting with the lava and rising steam is spectacular!
Be aware that every trip will be different, as conditions are dynamic and changing all the time. On our trip, there wasn't a lot of lava flowing on the surface, but there was one visible stream flow about 2 ft wide glowing bright orange and flowing into the ocean, with 2 or three other streams coming out just above the ocean and emerging and hiding in the steam plume as the winds blew the steam around, giving and taking away peeks at the various lava streams. The scene is beautiful! There are floating lava rocks that sometimes have little orange glows that gradually cool and then sink into the sea, lava occasionally spatters into the air in small clouds of black or glowing orange blobs--we could have stayed there all day to watch the show! You are so close to the lava and even closer to the steam plume that sometimes you can feel the heat and humidity rising from the ocean. You can't get closer without being a volcanologist! We spent about 30 minutes at the lava before initially heading back.
As we started to head back to the ramp, a double rainbow appeared, along with a new break-out of lava from higher up the cliff-side. Much to our surprise and delight, the captain turned the boat around so we could go back for another 10 minutes to watch the new breakout ooze its way closer to the ocean!
On the return trip, the guide told us about the past lava flows and changes to the landscape, pointing out lava tubes, local beaches, and historical places along the way.
This is a much more intimate and easy-to-see trip than the larger (49 person) boat.
The only caution is knowing your level of comfort being on a smaller boat out on the ocean (Dramamine for those of you who get motion sick, although you'll be so enamored by the lava that you probably won't think about ) read more