Hemlock is not very rot resistant.
Spruce is a tougher wood, but some pines, like yellow pine, are much more resistant to rot under water. Yellow pine is often used in boatmaking.
Red pine is one of the most used woods in the country. It is not naturally rot resistant, however, it can be protected and treated to ensure that is it can resist rot.
Tamarac is a rot-resistant tree akin to spruce. It has little needles that turn brown in the fall and drop off. It makes excellant beams, much like hemlock.
Titanium is highly corrosion-resistant.
No
Lightweight,dimensionally stable and rot resistant
Redwood and Wolmanized Lumber
Although all wood will rot in due time but pine and oak will last longer
Redwood, cypress, and cedar are termite and rot resistant. These are softwoods and may not last as long as hardwoods.
The disadvantages of Ash wood is that it is not as rot proof or water resistant as other hard woods. If it is left untreated, it will rot quickly.
PRESSURE TREATED WOOD, CEDAR, REDWOOD