To push back a little…
You say “I don’t agree that they should be sent back”.
But then you go on to mention how many of them die in drownings. If you allow those who made it to stay you would actually increase the amount of men, women, and children who drown.
The way to reduce drownings is not to reward the behavior that caused it in the first place. I think a more sensible strategy is to setup asylums that offer food and protection in their home countries so all they have to do if they want to move to Australia is walk into one of these asylums and apply. If they are considered a “legitimate refugee” & no criminal record then they should be allowed to live in the protected zone or even immigrate to Australia.