In the same boat
In the same circumstances; facing the same predicament..
'In the same boat' originated in 16th century Britain. When Thomas Hudson translated Du Bartas' Historie of Judith in 1584 he formed a metaphor that equated being 'in the same boat' with 'having the same fate':
Haue ye paine? so likewise paine haue we: For in one bote we both imbarked be.
This phrase is unusual in that it is purely metaphorical.
The metaphor took some time to catch the public imagination but, in 1629, the clergyman Thomas Taylor used it again:
He is in the same boate which is tossed and threatned with the tempest, and is someway interessed in the common cause, and quarrell.
The metaphor clearly alludes to the fact that one cannot get off a boat once it is under way and imagery of people who are together in a boat sharing the same fate, whether they choose to or not.