Where can I get Lapras in heartgold soulsilver?

Question

I heard that someone can get lapras in unown cave if I'm not mistaken though I could be wrong I need help to complete my pokedex plz

Answer 1

Lapras can be found every friday in the Union Cave B2F. It will be floating in the water and lvl 20.

Source: http://bulbapedia.bulbagarden.net/wiki/Union_Cave

Answer 2

union cave but it is a static Pokemon (meaning it is encountered when interacted with)
he/she is more specifically found in bottom floor 2 of union cave.
as far as my memory beholds, union cave is near slowpoke well to the right. (someone correct me if I am wrong)
hope I helped and you can find this info on the pokebase website.
fyi this is both on gold and silver gen 2 and 4.