Sun decks are not bimini canopies, or a similar fabric cover, instead they are sturdy aluminium built structures that provide full sun coverage. The structure is strong enough to hold extra gear, and is built with a lighter aluminum. It is like a roof for the pontoon boat, and is designed to keep the boat and passengers protected from weather damage with full coverage from the sun. It is not designed to hold passengers but can hold the weight of gear and luggage.
Our upper decks are like an extra level on your boat. They create more boat capacity for gear and extra passengers. The upper decks are built with a thicker aluminum to handle multiple passengers and actually increase the size of your boat. You can stand, party, sun bathe, sit, etc. on the upper decks. You can even dive off an upper deck. It is not just a pontoon accessory, but designed and constructed as a pontoon expansion.