For me the green water is salt seas, the blue water is freshwater lakes, or runoff from a mountain. Tubes are rivers or shipping lanes that follow shorelines.
If you really wanna know what I think, read on.

I appreciate the opportunity to gather my current thoughts on this page.
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1. A nymph who holds a cross-staff in a 45 degree angle upward toward the right side of the page. This could be interpreted as trying to measure something either very high on earth, or in the sky. To the east? The way she holds it, is actually similar to how you would hold a cross staff with your hand, but it is not in the right position to measure with it, which would be with your eye very near the other end, it is as though that part is missing, that is why it looks to some like she is pushing it away or throwing it. Maybe it is combining various ideas. Anyway, a cross-staff is an early navigational tool used to measure altitude or the distance of an object above sea level or the horizon, dated 400 BCE - 1500 CE, Although they continued to be used into the 18th century, then they were replaced by better tools. Could "she" be using it to point the way to high things? i.e she is not looking, she already knows.
2.
I think the parasol looking thing above her is a river system.
3.
The finial at the center of the river system, indicates volcanoes are involved, whether they are active or dormant.
4.
The nebuly lines says it's marshy in places around or under the influence of its delta. The river system has over time drained into the Gulf, helping to create it.
5.
That is why she is in a bathtub looking thing attached the the cut out piece of tube, because bathubs are bays, tubes are rivers. Then below that there is an even bigger bathtub, being affected by the silt of the previous occurrences.
So where is this? As a hint, the page previous seems to me to represent the Euphrates and Tigris joining together, flowing into the Persian Gulf, with Logman, as he has been called in this forum, inside, being the mnemonic for the rest of the the shore of the Persian Gulf, the Strait of Hormuz & the Gulf of Oman, and the shore of Pakistan, each about equidistant as shown by the upright dividers, and it is a pretty straight shipping shoreline (thus treated like a river with one shore) with the exception of the SoH and the shore of Oman, for that, look at Logman's arms for the mnemonic to drawing that portion.
Where are we on f79v? The Indus River system is the next thing past the curve in the shoreline after the long straight bit. Its rise is in a high rift created when the Indian continent merged with Asia. So the height story makes perfect sense to be mentioned, although evidently there is a higher river along that same rift to the East. Then we have the Gulf of Kutch and the Gulf of Khambhat, which are the next two features on the same shoreline going south.
6.
The nymph in the second tub points a ring toward the interior of India, it could be either a sociopolitical ring, ie further you will find different rulers and people. Indeed this area described did trade differently but more exclusively with the west, whereas the rest of India traded moreso with the East. Or it could mean "there's gold in them thar hills". The other ring also points to a place known for gold, and also being ruled by a different group than the one pointing, on f80v.
7.
With her other hand she points across the sea to the Gulf of Aden. The angle of her arm seems a good indicator of the angle of this crossing.
8.
When we go that way, we have 3 main choices, Persia, Aden to the Red Sea, or along the African coast. We choose the central choice.
9.
This allows us to choose from various ports along the way, ports are the shorter tubes, or river deltas.
10.
So here it does a bit of obfuscation in that the Gulf of Aden joins the Red Sea from the other side than the one shown. I have my thoughts about this but I would need to prove that anyone could see the things I have correlated so won't go into that here. Anyway I do believe this lower body of water is the Red Sea. The layout has shifted from north up to east up.
11.
The nymph is the first human, she incubated in the fish's mouth as per Anaximander's idea to explain how humans could have survived in an inhospitable prehistoric world (he was one of the first geographers, whose extent of the world ended at the Red Sea) and now the hard armour of the fish cracks and she can leave the fish and live on the earth as an adult. The earth in that area is pocked with volcanoes, but this could very well mean it was a comfortable place during the ice age, for instance.
12.
Other animals represent volcanos and volcanic islands that occur or occurred in and around the sea on the southern end and to the west.
13.
The two gulfs to the north of the Red Sea are softened into slight bumps in the shore. However this was a trend in portolan maps of the time. Take a look at the Catalan Atlas Red Sea from 1375, but they were even more blunted in the Angelino Dulcert versions of 1339, 1325 etc.
Are your eyes uncrossed now, or did I make it worse?