Trying to find an old anime/cartoon (pre 2003)

Hi all,

I am desperately trying to find an anime/cartoon I watched as a child between 1996 and 2003. As time has passed, I can only remember a few details, but maybe it will ring a bell for someone?

• There was a ship on water. On the ship, there was a surprise appearance of a skeleton in a (marine) uniform (white?).
• A male protagonist with a dog (or similar).
• There were many dead people lying next to each other.
• One of the protagonist's friends/family also died.
• There was a scene where the protagonist and the dog (or another companion) fell asleep together.

I remember the anime/cartoon being very sad/tragic and it really touched me.

Sorry for the few details — it was a very long time ago. Many thanks in advance!!