BBC reporter Paulo Cabral is travelling along Brazil's Sao Francisco river, following in the footsteps of Victorian explorer Sir Richard Burton. Each week day Paulo will be posting a diary entry on the web, and responding to a selection of your e-mails.
1 July: Petrolina
The Brazilian tropical fruits produced in Petrolina can be bought in most European supermarkets. They are delicious there, but eating them fresh off the trees in the company of the farmer who grew them - well it just doesn't get any better!
In October 1867 Captain Richard Burton, wrote of nearby Juazeiro: "Grape growing will hardly be possible in this climate where the hot season is also that of the rains. The same bunch will contain ripe, half ripe, and unripe berries which make a good vinegar."
Several cities grow fruits along the Sao Francisco River. Contrary to Burton's predictions they even have vineyards producing wine for export.
'This one feels just right' - Paulo
This has only been possible in this semi-desert region thanks to extensive irrigation with waters carried 40km from the river - known here as Velho Chico, or Old Frank.
This has been particularly well executed in Petrolina - whose name, by the way, has nothing to do with the oil industry.
Petrolina did not exist in Burton's time and yet it's now far bigger than its twin (and sometimes rival) Juazeiro, on the opposite bank of the river. Its once-dry fields, typical of this region (the Caatinga), are now bursting with mangos, coconuts, guavas, bananas, grapes and many other exotic fruits.
Even though diverting water from the river for irrigation will always have some environmental impact, Petrolina producers have minimised its effect. Their efficient use of water compares favourably with other irrigated areas, were water is often heavily wasted.
But the fact that water is more readily here available also has its drawbacks: people tend not to take so much care with it.
Water from the Velho Chico helps to grow fruit for export
More than once, kind employees in petrol stations volunteered to clean my car (which got covered in grime from the 1000km drive here). But instead of brushing it with some water to save the precious liquid, they just poured water all over it, wasting more than washing.
Good irrigation projects like the one in Petrolina should be taken to other cities in the Sertao, the Brazilian interior. But for that to succed we need government initiatives untainted by the kind of political interests that sometimes mar such highly visible public works.
And people have to know that whilst we can use the resources nature has offered us, they are merely on loan to us from future generations and we must make every effort not to damage them beyond repair.
30 June: Petrolina
Every year since 1941 hundreds of Brazilian cowboys have gathered on the Sao Francisco riverbank in Petrolina for a noisy and happy religious service.
Generally Catholics, they pray and sing to ask for help to breed their cattle in an area where food and water can be a difficult issue for oxen and men alike.
It's also a party, though, and a way to preserve their culture. They sing the "aboio" - inspired by the sounds they use in cattle herding, play the horn and reminded me almost of rap artists as one after another they ad-libbed in praise of God and with tales of the hardships in their lives.
Hundreds of cowboys take part in the ceremony
They come from afar riding horses, wearing traditional leather gear and hats that look nothing like those worn by John Wayne.
And they keep alive the customs of their ancestors, in spite of the slow disappearance of their livelihood, which has fallen prey to a more industrial approach to cattle farming in these parts.
I got quite another impression, though, when I went in town to a Forro (pronounced Foho) party and enjoyed the characteristic rhythm of traditional music from the Brazilian interior.
The band's traditional acoustic instruments were accompanied by electric guitars adding a modern pop flavour that I found disturbing.
It was the same reaction I had when I went to Jamaica, expecting to hear only - or mostly - roots Bob Marley-style reggae and was disappointed to find that things there had moved on a lot.
At the end of the night, I realised that the problem lay with me - that living in a big city I'd expected such music to be held in something like a time capsule, instead of seeing the music as a living thing, evolving with the communities who created it.
After all, cultures are always dynamic and ever-changing. Would somebody expect to go to Britain and listen only to Beatles-style rock'n'roll?