Translation of sólido

The machine arrived in Cuba at nine and it was already dark. The border control was nothing like the one in Mexico. They were communist and one could see the strictness and uneasiness of them.
I have your letter sitting on my desk. But, in the last 2 months I have been working on some projects which were very time consuming. I will not be able to start anything new before October or November.
Swimming in the open water was refreshing and fun and some of us jumped of the roof of the boat into the deep waters. After another snack break the four of us were invited for a Kayak excursion.