The answer to both the questions is an unequivocal YES. They can do both very well. I suppose this is to be expected as the tiger is the world’s largest cat and all cats are very similar in their athletic abilities.
As for swimming, tigers can swim well and during the hot season in India and in other places they often spend most of the daytime lounging around in streams and ponds half-submerged.
Surprisingly, there are records of tigers sometimes visiting islands in the Sunda Strait. By my calculation the nearest island is about 4 miles or so from the mainland and there are strong tidal currents of more than 4 km/h in that area. This surely is strong evidence that the tiger is a powerful swimmer and that they like water.
Some wild cat species prefer water to dry land and do most of their hunting in water. These are the “water cats” as I’ve described them. The tiger is not far from this category.
As for climbing trees, all cats like to climb (they like to move vertically as well as horizontally) and at the very least are competent climbers. Some wild cats are specialist climbers and these species of wildcat are tree dwellers. They actually live in trees.
The tiger is a large animal and therefore it is not as agile as a small wild cat when climbing but the tiger can climb and will climb when provoked although it quite rarely happens.
In Chitwan National Park, Nepal, a tigress with newborn young was annoyed by the presence of researcher in a tree near her den site. She raced up the tree and pulled him from his perch which was 4.6 m above the ground. Once again this is surely excellent evidence of the ability of the tiger to climb trees.
There have been other observations of tigers climbing trees. On one occasion an adult tiger climbed a smoothed-barked tree to a height of 10 m (this is about 30 feet) and in Bangladesh during the floods of 1969 it was reported that many tigers escaped the floodwater by climbing into trees.
Source: myself and Wild Cats Of The World by the Sunquists.