* The historian delved through dusty archives, seeking clues to the past.
* The detective delved deep into the case, determined to find the truth.
* The archaeologist delved through the ruins, carefully uncovering artifacts.
* The author delved into his memories, drawing inspiration for his next novel.
* The scientist delved further into the complexities of quantum mechanics.
In each of these sentences, "delve" suggests a deep, thorough exploration or investigation, even if it doesn't explicitly say "into."