Blue car rentals accept debit cards. They are located at the airport and have an office in Reykjavik. They are an Icelandic company.
great reviews.
All the best.
Look into the forest lagoon. It’s new in the last few years.
Open until 11:30 pm
i believe they provide a free shuttle from town
it’s only 5 minutes out of town.
$50 ish
Hope this helps