A remote camera release is a good idea but not essential.
You might like to carry a polarizing filter and a neutral density filter for enhancing sky and water.
A black card, a bit smaller than A4, is very handy for cutting flare at dawn and sunset, when your lens hood doesn’t cover.
A few memory cards is a great idea as our trips provide so may great opportunities to burn up some memory, especially if you’re shooting raw.
I’ll bring a computer so that we can view your pictures - you can bring your own, however not bringing it may help keep you under the target baggage weight of 10kg.
Don't forget your various chargers and spare batteries.