Up the creek wiithout a paddle
This phrase may have come from Haslar Creek in Portsmouth harbour, a 'salt' creek (may be origin of alternative 'up a #%&*$# creek'). Wounded sailors during Nelson's time, were taken there to be admitted to the Royal Naval Hospital Haslar to die or recover. The ships moored up in the Solent and the wounded soldiers were transported up Haslar creek by tramline hence 'Up the creek without a paddle'. They were held prisoner so that they would not desert while being treated, and some tried to escape by going through the sewers to the creek (another suggested origin of the alternative 'up a #%&*$# creek'). Without a paddle this would be hopeless, hence the phrase 'up the creek (without a paddle)' to mean being trapped, stuck or in trouble. Much very obscure navy related jargon entered popular culture in the seafaring peoples of the British Isles, and thus entered the English language as a whole.