Help w/ Itinerary from 9/25-10/1

Can you update your profile to say where you are from?

If flying in from the states, your first day is way too busy. An hour drive to Reykjavik, do stuff, and then another hour and a half to Hotel Rangá is too much.

I think you need a guide to go to Katla Ice Cave.

Newark. Arrive 7am.

Here is an updated itinerary that might seem a little more organized but I welcome your input:

9/25 7:00AM Arrive KEF Airport. Budget rental car - pick up your keys in the terminal and walk outside to the 2nd parking lot.
1. Tour Grindavik – Active Volcano
2. Lunch in Reykjavik, Art Galleries
3. Stopping after ~1 hr+ @ Olis Selfoss for gas fill up.
4. Hotel Ranga
9/26
1) Seljalandsfoss – 360 degree waterfall
2) Skógafoss
3) Dyrhólaey (lunch and gas stop) to lodging for the night - long drive day
4) Hotel Jokulsarlon - Glacier Lagoon Hotel

9/27
1) Diamond beach @ Low Tide (https://www.worldbeachguide.com/iceland/diamond-beach-tide-times.htm#)
1) Book Jökulsárlón Glacier Lagoon Boat Tour
2) Book Ice Cave tour
3) Snowmobile
4) Hotel Jokulsarlon - Glacier Lagoon Hotel
9/28
1) Yoda cave
2) Katla Ice Cave
3) Vik Horse Adventure
4) Solheimasandur Plane Wreck
5) Umi Hotel
9/29
1) Lava Center Museum
2) Urriðafoss Waterfall
3) Kerid Crater
4) Gulfoss Waterfall
5) Geysir
6) Thingvellir
7) Hotel Grimsborgir by Keahotels
9/30 –
1) Insidethevolcano.com Tour
2) KEF Helicopter Tour
3) The Retreat Blue Lagoon

It is unlikely you will be able to "tour" the active volcano in Grindavik - currently locals can't even get close. Also the Blue Lagoon has been closing intermittently so you'll want to check if they're open closer to your arrival date. The current info about volcanic activity/restrictions is here: https://en.vedur.is/about-imo/news/

I agree that first day is probably too much especially jet lagged. Also the plane wreck is a solid 45-60 minute hike each way, make sure you check daylight hours and plan accordingly, you do not want to be hiking back in the dark.

IME days 1,3 and 4 are way too busy. As mentioned you will not get anywhere near Grindavik as the authorities are keeping people away for their own safety.

Thanks for input.

I removed the volcano visit on the first day, and the airplane visit on the 3rd day.

This is perfect feedback.

9/25 7:00AM Arrive KEF Airport. Budget rental car - pick up your keys in the terminal and walk outside to the 2nd parking lot.
1. Lunch in Reykjavik, Art Galleries
2. Stopping after ~1 hr+ @ Olis Selfoss for gas fill up.
3. Hotel Ranga
9/26
1) Seljalandsfoss – 360 degree waterfall (Gljufrabui also)
2) Skógafoss
3) Dyrhólaey
4) Hotel Jokulsarlon - Glacier Lagoon Hotel - 2 Nights

9/27
1) Diamond beach @ Low Tide (https://www.worldbeachguide.com/iceland/diamond-beach-tide-times.htm#)
2) Book Jökulsárlón Glacier Lagoon Boat tour – Zodiak
3) Book Glacier Snowmobile tour
4) Hotel Jokulsarlon - Glacier Lagoon Hotel - 2 Nights
9/28
1) Yoda cave
2) Book Katla Ice Cave Tour
3) Book Vik Horse Adventure
4) Umi Hotel
9/29
1) Lava Center Museum
2) Urriðafoss Waterfall
3) Kerid Crater
4) Gulfoss Waterfall
5) Geysir
6) Thingvellir
7) Hotel Grimsborgir by Keahotels
9/30 –
1) Book Insidethevolcano.com Tour
2) Book KEF Helicopter Tour
3) The Retreat Blue Lagoon