Shore diving at Koloa Landing we saw several giant sea turtles, eels, about 50 different kinds of fish. Snorkeling at Beach House (south shore near Koloa) also was very good. SeaSport Divers were very good for boat charters. Enjoyed driving up Waimea Canyon as far as it goes. Several good hiking trails in that area that were easier hikes than the trail that goes along the Na Pali Coast. We only made it about a half mile on the Na Pali Coast trail - steep and slippery, but the views and scenery are worth it for even a very short hike.
The Kai Guava Plantation was fun to visit. The Macademia nut ice cream cones are terrific. We also enjoyed the coffee plantation and all the free samples of different blends of coffee - we came home with several bags of Kona coffee - and we usually only buy Starbucks. It's very good. Our favorite drive was through the tree tunnel on the way to Koloa.
Quick Tips:
It's not the best island for scuba diving, but it was still pretty good and there were plenty of other things to see and do. Kauai is appropriately named "the garden Island". Most of the island is lush and green. We had sunshine the whole week and only occasional sprinkles of rain. It rained a lot in the mountains, but close to the ocean, it was usually sunny.
Best Way To Get Around:
Renting a car at the airport was easy. We drove all over the island and covered every main road, but only used two tanks of gas in a week.