This would be my dream place to visit, and maybe you and your wife would like it aswell
https://www.getyourguide.com/-l5049/?cmp=ga&campaign_id=332262569&adgroup_id=28654554809&target_id=kwd-39876250&loc_physical_ms=9069657&match_type=e&ad_id=192677470747&keyword=blue%20lagoon&ad_position=1t1&feed_item_id=&placement=&partner_id=CD951&gclid=CjwKCAjw0JfdBRACEiwAiDTALsCB_cgsacZ_BPP8NsV6GxGUF4SbRYaRhcFRaf9v8uQVAEtYXEuNvRoCeLcQAvD_BwE
We have already been there, but nice. Most German SPA will be a better experience.