An outside pocket on the lens case holds my 1.4 teleconverter. These are carried either wrapped in Domke wraps in the backpack or in my Xtrahand Vest made by Vested Interest. My Gitzo tripod lashes to the backpack with straps and bungie cords that are part of the pack. This leaves my hands free to use a walking stick. Rain-gear, snacks, and emergency supplies go in a top outside pocket which fastens down over the pack, further protecting my equipment from rain and salt spray when making boat transfers.
Water bottles are in holders on the side of the pack, angled forward for easy access.
I use my Tenba backpack, the PB large, which fits in the overhead for carrying gear on planes. When traveling by air, I ship the Eureka frame pack in a military type duffle bag with checked luggage. Then I store the duffle bag and the Tenba backpack at my friends' home in San Jose before heading out into the jungle with the Eureka frame backpack setup. I also use the Tenba backpack when doing nearby trail photography and when working out of my vehicle in the U.S. I normally carry more lenses when working on short trails or out of my vehicle, and the Tenba works great in these situations. Additionally, I use the Tenba 600mm long lens case.