Hi there, glad to see that your nick implies that you like to have adventures, this certainly isn't an easy one. However here's what we've found ....
Train via London : £46 per person one way plus underground ticket.
SOUTHAMPTON CENTRAL dep 09:25 LONDON WATERLOO arr 10:52
The take the Underground to STRATFORD (London) 23 minutes
STRATFORD (London) dep 12:09 MANNINGTREE arr 13:20
MANNINGTREE dep 13:26 HARWICH TOWN arr 13:47
London Underground pdf at http://www.tfl.gov.uk/tfl/pdfdocs/colourmap.pdf
Waterloo is top of square E5, Stratford is middle of C8, note though they are connected by the silver line (Waterloo & City Line), this
is closed on Sundays. Best bet, North on the Black (Northern) line to Tottenham Court Road, then East on the red (Central) line.
Private Hire Cab :
171 miles, all the way round the M25, could be around 3 hours - negotiate price ahead of the journey if you can.
Have you checked if Royal Caribbean are providing any sort of coach pick up? If they are collecting from London Victoria Coach Station, then you can get there from Southampton in 3 hours, depart Southampton 09:30 arrive 12:20 - prices from £1 if booked online http://www.nationalexpress.com
. Slightly later one is faster, leave 10:30 arrive 13:05.
We'll try & think of other ideas, but if you want more info about the options, please feel free to ask.
Alan & Katrina in Southampton, UK