Ways to minimize leptospirosis: The disease is spread in rat piss. So ideally if you can find a stream away from the city and in high rainfall areas, you'll minimize the rat piss ratio. If there has not been a good rain lately I would limit my stream swimming to these relatively pure areas (like the seven sacred pools near Hana, Maui).

If there has been a major rainfall, we assume most of the system has been flushed out and we'll swim in the more urban / downstream areas like Kapena. (Kapena is as far urban as I'll go.) I'm not sure how the disease enters the body, but if you do not get cut, don't drink the water, and don't let water go shooting up your nose when you take a jump, you'll also minimize your chances.

A simple pleasure in Hawaii is hiking back in towards the center of the island. (If you don't know, the center of the island is usually mountainous, which causes rainfall, which gives us our drinking water and lovely forests and streams.)

Almost all the valleys and ridges have some sort of trail, and (famous last words), you'll do pretty well just exploring. There is a hiking book, with a title something like "Hiking in Hawaii" that is not too expensive. Pictured is the second waterfall going back in Waiomao valley.

Some of the waterfalls have enough water to swim and even jump in. This is obviously a dangerous activity, and I'll only give a couple of warnings. These mostly apply to urban spots like Kapena falls (pictured). (This is not the best spot, but it is the easiest to get to in Honolulu.)

First only jump where people who are surviving are jumping. This will generally be right where the water dumps over the falls. There are rocks, etc. in other places.

Second watch out for broken glass. The wisest thing is to wear some old shoes (or those reef walkers) to protect your feet. The safest places to get out are usually the rocks by the falls. (As opposed to walking on the bottom in the gravelly areas down stream that may have broken glass.) The safest places to hang out are the open rocky areas in the sun. (Besides broken glass, there are lots of mosquitoes in the shady underbrush.)

Third watch out for a weird disease called leptospirosis. I've taken lots of people to Kapena falls and no one has gotten more than a mild headache. But I think occasionally it gets more serious. There are usually signs posted in places where people have gotten it. If you are going to ignore the signs, at least consider the common sense approach we use.

Mountain apples are very mild and juicey, sort of like a pear. However, they are a little trickier to find and very tricky to pick. They grow in the wettest areas, so more likely on a valley hike than a ridge hike, and more likely deeper in the valleys. They tend to grow out of reach. The best tool I've found is just a long stick with a forked end. Have one person shake the branch and another catch the falling apples. The redder ones fall off easier and are sweeter, but I like the half white ones best.

Passionfruit (lilikoi) are maybe the best of all the wild fruits that get ripe in the summer. They keep well (most of the others do not), and are fairly easy to get if you find them. Most are bright yellow, egg shaped, and have a hard outer skin that feels like plastic. (There are also purple and pink varieties.) They tend to fall off when ripe, so often the way you spot a vine is the fruit laying all over the ground. (The vines are often out of reach.)

To eat a passionfruit, you can just rip it open, but the best is to cut the skin only (about a 1/4 ") and pop in half. If the seeds and juice are still in their little packets (versus in a juicey mix), the fruit is still good no matter how old the outside looks. (The old wrinkly ones are actually tastier.) If you've never tasted passionfruit, be ready for a mild shock. The taste is very strong and very sour, but it is killer good.