Advice on a Carry-On Camera Backpack

Hi everyone,
I’m currently using a Lowepro Flipside 400 AW, but I’m really pushing its limits in terms of space for my underwater gear. Since I still have a bit of room left within the typical airline carry-on limits (55 × 40 × 20 cm), I’m considering upgrading to the Lowepro Protactic BP 450 AW II, which seems to make better use of the allowed dimensions and offers a noticeably larger usable interior.

The only downside: the Protactic weighs 2.7 kg, which is about 1 kg heavier than my current Flipside. It’s not ideal, but still acceptable if it solves the space issue.

Before I make a decision, I’d love to hear your experiences or suggestions regarding carry-on solutions for underwater photo gear — especially from those traveling with a similar amount (or even less/more) of equipment.

This is what absolutely needs to fit inside (also shown in the picture, stored in above mentioned Flipside 400):

• 1× Fantasea RX100 housing

• 1× Sony RX100 VA

• 1× INON UWL-95S + Dome Unit

• 2× INON S-220

• 2× video lights (similar size to the S-220)

• 2× small storage boxes (O-rings, tools, small parts)

• 1× INON UCL-90

• 2× diffusers for the S-220

• 8× 18650 batteries

• 8× AA Eneloops

• SD cards & Sony camera batteries

Bonus if it still fits:

• Chargers, cables, adapters, etc.

  (everything heavy and sturdy such as arms e.g. are in my luggage anyway)

If anyone has tried the Protactic 450 as hand luggage (or can recommend alternatives with good interior space that still work as carry-on), your input would be greatly appreciated.

Thanks in advance!

Edited 1 hour ago1 hr by Apneagraph