SEARCH I2P
Search I2P sites on the deep I2P web
https://zqktlwi4fecvo6ri.onion.to/wiki/I2P_links

GRAMS
Search the deep web the always-popular darknet search engine Grams
http://grams7enufi7jmdl.onion/

TORCH
Search TOR using the excellent TORCH search engine
http://xmh57jrzrnw6insl.onion/

AHMIA.FI
This is a very nice search engine for the deep web which can be used on the clearnet.
https://ahmia.fi/