What to use to fix a cable underwater?

[OCuea]

Any ideas on how to connect a cable carrying 12volts and 1 amp that will be permanently submersed please. I thought of soldering and covering with sealant then heat shrink and repeat but I think there are gel filled connectors a bit like wagoo ones but have never used and do not know if submersible. I also found two other solutions but do not have the wire thickness on me at the moment. Has anyone been there and done it, and have a recommendation please.
Hylec 2-Entry IP68 Gel In-Line Connector Black - Screwfix

Power Cable Connector Joint CUJ-02

 

[[199490]]

Unless you need to get back into the join, I'd either:
(a) Use a Scotchcast potted joint as illustrated in this video

- if there isn't one the right size for your cable you can make a mould up with any suitably sized PVC tube (about twice the diameter of your cable) and buy the resin by itself
(b) solder as you suggest and wrap tightly with Scotch 23 self amalgamating table, layer of Scotchkote sealant, and a layer of regular electrical tape to provide mechanical protection
In eaither case make sure you abrade the jacket of the cable so the tape/sealant sticks, splices usually leak at the ends

 

[OCuea]

I will now attempt the repair thankee for the info

 

[andsarkit]

I have used solder covered with adhesive heatshrink then sealant and a final covering overall of more adhesive heatshrink. This was on connections for multiple hydrophones on a seismic cable and it was unusual to have a failure.
Some 2 core cable is oval and may not seal well in a cable gland. if the cable is round then Bulgin Bucaneer connectors work well or the inline connector you found should be fine. The IP68 rating should also specify a depth and duration to give you more confidence that it will last. Also the cable glands have a limited range of cable sizes for effective sealing.