From my reading the DeLorme Inreach satellite messenger would be the best option for SOS and sending/receiving messages. It is water resistant. Cons are that you absolutely have to have a clear line of sight to the sky, or else the signals or messages will not go through. Annual subscription cost too.
The alternative version would be the ACR ResQ device. It does not have two-way messaging. SOS signal strength is strongest even compared to the Inreach. No subscription fee - only possible cost could be the 5 year cycle battery ($$$)
With these devices I could get SOS and message family and friends (whether there is an emergency or not)
Satellite phones on the other hand would cost more with much more versatility - calling, texting - and I would go with the Iridium sat phones on a postpaid plan.
It is nice putting these ideas together though. Need more reading and reviews though.