In the Guyanas, at least, the boundaries are obvious:

 
From Guyana to Suriname, a river, no bridge, but a ferry.

From Suriname to French Guiana, a river, no bridge, an unavailable ferry, but pirogues. The guys are sturdy and skillful. Everything went fine.

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From French Guiana to Brazil, a river, a new bridge that is not open yet, a ferry that does not arrive and canoes. The guys here are less sturdy, but clumsy and drop my bike to the ground. It does not fall into the river, fortunately, we manage to the catch it; unlike my helmet, which gently starts floating away. We fish it from the water, but the electronics of my Bluetooth GPS did not like the bath, and decides to go on strike. For today it's no big deal; where I go now, I cannot miss my road, there is only one. Well, road might not be the right word, today’s program is trail and dirt roads. This is the stage that I fear most, after all I heart before I left,  I am prepared to the worst.

 
Well, regarding the tracks around here, it is better to be like St. Thomas, and just believe what you see. There were a few hundred km of dirt road of course, but this was nothing, compared to what I experienced in Guyana. It's a beautiful and good track, with almost no holes. Unlike in Guyana, today seems to be my lucky day, because, in addition, it does not rain. This is only the third day without rain since I left Mexico City two months ago! I am basically alone driving here; I cross a car every hour. So I rev up, the needle on my speedometer goes crazy, peaks at 150 km / h, I get intoxicated by the speed and the adrenaline rush. The road is sometimes a real rollercoaster, and flying up the steep slopes, I often have no clue what might come across on the other side. This is madness, I must to slow down! Often, on the bottom of the waves, there is a wooden bridge, not always in good condition, but always good enough for a scare, a brake to death and a cold sweat. But this is the only common point with my crossing the tropical forest of Guyana.

After a rather tricky section with road works, the trail gives way to a superb and brand new asphalt road. I almost regret that it's over. But I'm so well advanced on my schedule that I continue to Macapa straight away; and in one day, I manage to do what was planned for two.

……….

I am in Macapa now, about thirty kilometers north of the equator, at the Amazon bank. The road ends here. Now I need to find a boat to take me up the river to Manaus.

……….

I am lucky again: Thanks to my double stage from yesterday, I can catch a boat today. Otherwise I would have had to wait five days.