The most obvious way to get to the top of a tree is to climb it. But climbing trees to reach the rainforest canopy is a lot like climbing a mountain. It's a long way to the top and there isn't much to hold on to. Basically, you need lots of rope and a way to get it high enough into the trees that it can be climbed or used as a pulley to haul equipment and explorers into the towering branches. As far back as the late 1920s, cannons were used to fire ropes into the canopy and those ropes were then used to haul scientists to the top. Ladders were also a popular way of exploring the canopy, at least for smaller trees. More recently, slingshots have been used to shoot fishing lines into the trees that can be used to raise more substantial climbing lines. By the 1970s, rainforest scientists were using a wide array of mountain climbing (and even cave-exploring) techniques to scale these huge tropical trees.
Once in the treetops, the explorer's adventures are hardly over. Platforms have to be hauled up and placed in the branches to create a base from which research can be performed. And there's danger aplenty on those high branches. These dangers include not only falling to the ground like a human meteor, but heat, dehydration, and -- maybe worst of all -- insects. Massive swarms of bees and wasps can be deadly to a scientist who gets them angry. Troops of ants can produce acid that eats right through the ropes holding treetop platforms in place. Forget about the danger of predators on the rainforest floor. The insects in the canopy can be every bit as deadly.