Hi Sayali, Don't go to tarkali if you are looking for off beat destination. I have done scuba in malvan in off beat place last week only. I can share the contact details of resort and scuba diving person.
Please DM me for more details.
You can Visit Tarkarli Beach you will get low budget amount hotel or other option is The small town People will help you to stay with there house...
but just be careful if you are staying with local people