Update Two select box when change another select box I have drupal form with three select box i want to change select box 2nd and 3rd after change value of 1st select box.

ex:
i have Three select box

1) Cruise line

2) Destination

3) Ship Id

When user select any value of Cruise line then i want to update value of 2) Destination and 3) Ship id

2nd and 3rd select box value are dependent on 1st select box

your answer really appreciated 

Thanks in advance
Try one of the following module

Simple hierarchical select


  Simple hierarchical select defines a new form widget for taxonomy fields to select a term by "browsing" through the vocabularies hierarchy.


Hierarchical Select


  This module defines the "hierarchical_select" form element, which is a greatly enhanced way for letting the user select items in a hierarchy.


Or you can also achieve that by writing a custom module :)